While I was looking through pokemon card databases, I discovered that the early Team Rocket set has unique pokedex entries! It's great not only for just being more pokedex data but because it's about an area of canon we don't usually see. The entries seem either written from the point of view of a member of Team Rocket (several of them seem to focus on capturing that species) or an outsider remarking on a trait present in Team Rocket pokemon without realizing that's why the pokemon are behaving abnormally.
Now, this set introduces the "dark" modifier, not to be confused with the type that would come out very shortly afterward. Although the set contains basic pokemon, only evolved ones can be "dark", and although the entries are overall pretty edgy, it's only the "dark" ones that have entries talking about hyperaggression or flat affect from the pokemon. Additionally, given they have lower HP than the non-dark cards do, the consensus from fandom at the time was that the "dark" modifier was added by abusing pokemon.
So, what entries do we have?
Abra: It teleports itself away from danger, making it difficult to capture.
Abra was of course one of the pokemon you could get from the game corner, and quite cheaply at that. Given they're relatively rare and teleport away on the first turn, the Team Rocket members in charge of keeping the abra bin full must get pretty frustrated, but that's the same reason this not particularly useful pokemon is valuable enough to keep it in stock. Probably they found some way of addressing the "difficult to capture" issue, like drugged bait.
(Dark) Kadabra: Some people say that Kadabras are responsible for many of the mysterious events reported in the news.
I feel like this is a specific reference as well, but I'm not sure I can think of anything. It presumably ties into the various activities Team Rocket was getting up to all game, so perhaps they rely on psychic types to confuse things just enough that witnesses don't have a clear idea what happened.
Certainly if the Generations shorts are anything to go by, the authorities were struggling with even basic, basic facts and ended up blindsided by the revelation that Team Rocket's powerful boss whose base was at the center of Giovanni's gym was Giovanni. Admittedly, it's also game canon that the NPC helper you meet at every gym has no idea who the eighth gym leader is when it's written on the pillar he's standing next to, so perhaps this means that there's several terabytes worth of cellphone videos showing clearly showing various kadabra doing these things while a guy in a Team Rocket suit shouts, "Yes, my kadabra, cause this! You and I are completely responsible for this otherwise mysterious event! Mwahahaha!"
(Dark) Alakazam: Almost as if it were being controlled by something else, it never changes expressions, even in the middle of battle.
My first thought for this one is that it's actually possessed by Mewtwo - given alakazam are extremely powerful psychics in their own right, it's hard to picture what else would be controlling one. And it's intriguing to think about the idea that Mewtwo starts exerting more and more influence over the gym battles as time goes on, even when not visibly present.
The less elaborate answer is that the description is just meant to emphasize how emotionless the alakazam is and how it's become just a tool to its trainer, which is in line with much of the text about other dark evolutions.
Charmander: Many people find it cute and try to hold it, only to be burned by its tail.
I feel like these entries are read very cynically. This person doesn't hate charmander or anything. They're not sneering about how cute pokemon are stupid, and they're not even necessarily sneering at the people who forget to worry about the tail. The focus, though, is on how people misjudge the situation and hurt themselves as a consequence.
The moral here may be that cute things can still hurt you, or that it's a lot easier to hurt people if you can look cute.
(Dark) Charmeleon: Its tail is incredibly strong, able to lift up to 5 adult men.
This one is maybe the weirdest one in its banality. Charmeleon still has that same flame and even one adult man would be hard pressed to fit on the tail without getting burned.
The card itself has the attack of tail slap, which may be the only reason this is there, but tail slap's weaker than the regular card's scratch attack, so it's not really selling the idea charmeleon have super-strong tails. Given this is so early in the franchise, maybe someone was concerned about the cards diverging from the games confusing kids and felt the need to explain why the card move tail slap did damage when the game move tail whip didn't?
(Dark) Charizard: Seemingly possessed, it spews fire like a volcano, trying to burn all it sees.
Our second "possessed" reference and more clearly meant to mean the pokemon is messed up. This context is why I think the alakazam is meant to also be traumatized, not literally possessed.
That said, this being Mewtwo acting out is definitely an interesting line of thought. It's gotta get boring hanging out under the gym and it seems he only got called out if a trainer was good enough to beat the rest of Giovanni's pretty imposing team.
Diglett: It follows Onixes in their tunnels, looking for scraps of food they have left behind.
This one seems like a perfectly ordinary entry. That said, it does have a focus on where you can find the diglett, so it's the sort of thing you'd need to know if you wanted to catch a lot of them.
(Dark) Dugtrio: Digs large sinkholes in the ground and tries to trap its enemies in them.
The less charismatic pokemon seem to get entries that are just "here's how you could kill someone with this guy".
Dratini: The capture of the first Dratini inspired the search for other legendary Pokémon.
This was the entry that made me realize these were different and worth checking out.
This is very early in the franchise, back when "legendary" was clearly a matter of what people told legends about and not some objective measurement. Arcanine were also considered legendary pokemon, possibly just for being generally amazing and possibly because stone evolution had only recently been worked out and before that, no one knew how to get an arcanine and they were either one-off fluke evolutions from a growlithe or found wild very, very rarely.
Next is the bit about this inspiring a search. The regular game lore of dratini being discovered only very recently is already quite interesting to me (particularly when tied with the fact they're being rapidly bred and/or rapidly removed from the wild to explain how the Safari Zone can keep them in stock), but here we have the implication that this is the opening to the legendary hunts that mark the rest of canon, rather than that this was always the way things were.
And then there's the question of just who is doing the searching. Given this is the Team Rocket set, it could mean everyone including Team Rocket starts looking for legendaries in earnest or it could mean that Team Rocket specifically starts searching but the general population isn't doing the same.
Could this be related to the mew expedition? That entire affair takes place before the events of the games and just the making of Mewtwo that happens afterwards is said to have taken "years", while dratini are said to have been found "recently", but even in Moon taking place a decade later they're still talking about the specific fisherman who pulled one up. Something as big as the discovery of a mythical pokemon doesn't exactly happen every day and certainly in the original games they're an established enough part of life and exist in great enough numbers to be used as an incentive for Safari Zone tickets, so I could see "recently" meaning something more like "within the memory of the person talking" if it's a pokemon that's been a myth for hundreds or thousands of years before that.
(Dark) Dragonair: As it is fitting for a legendary Pokémon, it has many strange powers, including the ability to make rain or snow fall.
This one appears to come from the anime's pokedex. Not sure if there's any greater meaning to be found there. The only odd thing here is that other dragonair entries all use much weaker language for their weather-altering power and that the original games describe it as a "gentle" aura, so the overall implication is that dragonair calm the weather while here the focus is on them changing the weather from calm to something else.
Tying the weather effects to a dragonair's mood or mental state could be interesting, especially since I can't recall anything much being done with this before.
(Dark) Dragonite: Sometimes called "The God of Destruction." Its wings are able to support it in spite of its massive weight.
My first impulse is to joke that Champions Lanc is an outlier adn should not have been counted, but on reflection, this isn't anyone's dragonite, it's specifically the "dark" variant. Also, this comes before Lance's appearance in the second generation where he gains the connection to Team Rocket and a reason why they might talk about dragonites as terrifying. Therefore, my guess is there's one guy in Team Rocket who has a dragonite and is really invested in convincing everyone else how cool and badass and not cute the pokemon is. He wrote this.
Drowzee: Not popular with girls because of its attitude. Can often be heard muttering to itself in a low voice.
I really have nothing to offer but WTF. There may be some translation issue going on here. It may be for the best.
(Dark) Hypno: Carries a pendulum with it always. Sometimes appears near less-traveled roads and schools at dusk.
Possibly this has to do with why the girls don't like them.
I don't think we see any suggestion Team Rocket kidnaps kids - they're an extremely popular fanon plot device for experiments that horribly give teens awesome superpowers and cool new hair colors, but in canon I think their whole "pokemon are tools" thing suggests a degree of human exceptionalism. It's more likely this is another non-charismatic pokemon getting entries about how inherently dangerous they are.
That said, they could want to kidnap kids for the traditional reasons of ransom money or leverage on their parents.
Alternatively, this is a rogue hypno and the idea is that the "dark" pokemon getting produced by Team Rocket trainers go on to become general menaces in the same way fighting dogs are dangerous even if they've run away from their abusive original owner.
Eevee: A rare and unique Pokémon about which little is known, as few have been captured.
Now, we're introduced to eevee by Bill, who already does know a bunch about them. Then again, the fact you have to look the entries up on the computer in his house and they don't even tell you anything but the name and appearance does suggest research is in its infancy.
This also reminds us about the fact it's never been clear where eevee come from. They've been found wild in recent games, but an idea I had as a play on how often trainers trip over eevee on their way to the first route was over time, eevee get released into the wild and establish feral colonies, only to rapidly become invasive. Later generations of the games generally take place later on in the official timeline, so that'd actually fit, as would the fact their habitat listing in FRLG was "urban".
This entry suggests that whatever was going on with eevee research, Team Rocket was the last to know. Now, the Game Corner does end up selling eevee in GS/HGSS three years later. They weren't officially part of Team Rocket by then, but given they keep supplying you with the same stock of explicitly stated to be poached pokemon after you rout the uniformed guys in their basement, they evidently retrained some connection. So my guess is that in the present of the cards, they've just got their hands on eevee. By the time of the RBY games, they're actively researching the pokemon and have a small breeding colony. When you beat Team Rocket, the research stock with no more research ends up absorbed by the Game Corner people, who just breed/sell the eevee in the GSC days.
And that, in turn, suggests Game Corner eevee could be slightly different from standard eevee, either with actual weird experimental quirks or just by being the inbred puppymill version because they're from a tiny founding population and sold by people who don't care.
(Dark) Flareon: A Pokémon with a hot temper that can't be controlled once it's angered. Capable of breathing flames hotter than 3000°.
So this is pretty standard, but a subtle aspect of this I really like is the normalization. The bit about 3000° is found in several pokedex entries, but this is the only pokedex entry that ever references flareon having a temper. Across every game and in the corresponding light flareon card, none will say anything about flareon having issues with their temper. This temper problem, therefore, seems to apply exclusively to "dark" flareon, but it's presented as if that's just how flareon are.
(Dark) Jolteon: A dangerous Pokémon when angered. It likes to playfully shock people with the electricity it stores within its body.
This one is a nice pair of facts in a different way. Again we're reminded that the dark evolutions have anger issues, but the "playfully" of the second sentence suggests it's not related to the first. When not angered, their idea of playing is to electrocute people for fun.
That's not just bad in general, it's a great issue for someone trying to rescue sad abused superpowered Team Rocket pokemon to deal with! Most of the time fic has abused pokemon, they're just sad and need cuddles. Rarely, things get as extreme as being aggressive for good reason against people who are bad. Here, we have a pokemon that's not just dangerous to everyone if not taken care of carefully, but is actively sadistic even when treated well. That's a much more difficult rehabilitation project than just telling Nurse Joy that you rescued an abused jolteon and deserve a parade for your heroics.
(Dark) Vaporeon: A Pokémon capable of controlling water, so it is capable of creating giant whirlpools.
Possibly just a poor translation, but the repetition of this one makes it sound like someone's explaining that the reason they got a vaporeon was because they wanted those whirlpools, and the way it says "capable of creating" instead of just "creating" strongly implies this isn't something they do on their own.
Of course, when Gold and Silver come out, there ends up being another reason for Team Rocket to really want a pokemon who can make whirlpools. The Whirl Islands aren't going to search themselves!
Ekans: A carnivore that swallows its prey whole. Pidgeys and Spearows are its favorite food.
And back to non-charismatic pokemon just get entries about being dangerous.
(Dark) Arbok: Freezes its prey with its stare. If you should encounter one, remember not to look into its eyes.
This one does go a step farther in establishing that they totally view humans as prey and that this happens so often that it's the most important thing to tell anyone when mentioning arbok.
Once again, it's unclear if this is being written from the point of view of a Team Rocket grunt or an outsider who's encountered their pokemon. The latter makes more sense here, but it's even more interesting to think that this is a problem Team Rocket faces. A lot of the entries here emphasize these pokemon are extremely angry and barely to not at all controllable, so there are probably a lot of friendly fire incidents. And that sort of climate would only encourage the pokemon as tools mentality over caring about their wellbeing, which makes for worse pokemon behavior, which further justifies treating them badly...
Grimer: It has recently been found that Grimers are formed in waste-processing plants, and can move into towns via sewers./ (Dark) Muk: Muks appear suddenly, spreading sludge everywhere. Whenever one appears in a city, panic ensues.
If the focus of a lot of these has been how pokemon can be harm humans, this one appears to be the slight twist of how pokemon can invade human areas. The rest of the pokedex entries about grimer talk about it eating pollution, but here they appear to start at highly polluted areas and then move into populated areas where they can do harm.
The bit about spewing sludge also carries the implication that they're not feeding on waste but generating more, either out of nowhere or out of previously non-toxic-sludge matter.
Koffing: First discovered in a weapons factory, this Pokémon can now be found almost anywhere.
Koffing are made of war crimes!
Actually, it might be interesting if these were in some way related to gastly. If those are poison gases tenuously held together to amount to ghost/poison type, maybe koffing could be what happens when there's so much poison they can form a solid body and drop the ghost typing. Back in RBY gastly's pokedex entry wasn't really in line with the idea they were actual ghosts but weird things from another dimension that happened to have very insubstantial bodies like ghosts do in stories.
(Dark) Weezing: Researchers have observed these Pokémon reproducing in industrial waste sites.
A pretty meh entry by itself, but given koffing are evidently less smog and more mustard gas, the idea weezing can use industrial waste to reproduce suggests they're refining it into significantly more deadly forms.
This actually seems like a much better fit for the environmentalism message of the pollution pokemon quartet than the idea that they're eating up our pollution. Grimer and muk multiplying pollution and bringing it into areas trying to keep it out, koffing and weezing manufacturing toxic waste into far more toxic waste.
Mankey: Normally friendly, it quickly becomes angry if it doesn't get what it wants.
As I keep mentioning, these were written very early on in the franchise, and so this highlights how flanderized mankey have become. Mankey were shown in the anime and manga hanging out and chilling in tree branches and their original pokedex entry backs up that they were supposedly to generally look docile and harmless and their sudden ragefests were a surprising contrast. By the second generation, though, the focus was already on them being nasty and ill-tempered all the time. It's a shift made all the weirder by the fact it turns them into just second-rate primeape. Possibly it's a general rejection of the the idea of pokemon having distinct behavior differences between evolutions - although I like it, it is a bit at odds with the anime's focus on pokemon with individual personalities. Then again, it was the anime that pushed hardest on there being this distinction, claiming mankey were "usually" calm in the pokedex there, plus it had multiple episodes support the idea that personality changes could happen with evolution.
(Dark) Primeape: Although Primeapes have always been mean, lately they seem to be becoming even more vicious and frenzied.
This seems almost certainly an entry written by an outsider, where the issue is that Team Rocket is causing an increase in aggressive, dangerous pokemon but the rest of society doesn't realize the common thread between certain trainers.
However, it could also be related to their ongoing poaching activities. Human poaching is known to cause a lot of behavioral changes in the animals targeted. Perhaps areas poached by Team Rocket end up containing more vicious pokemon, at least in some species lines, and this is written by an increasingly nervous Team Rocket poacher who would really like it if HQ could get back to him about the tank.
Machop: It's said that not even pro wrestlers can take down a Machop.
Of course, Stadium says machop are stronger than a hundred men, so this is really underselling the difficulty. The main difference here is that this entry suggests human vs pokemon matches have actually happened. Maybe this is just a warning to overenthusiastic recruits that this is one of the pokemon not to grab directly when trying to steal them.
(Dark) Machoke: While normally peaceful and friendly, the number of incidents involving cruel Machokes is rising.
The opening of Hoenn famously has machoke as movers and they're also found moving things in Goldenrod, but this is perhaps the first reference to them being generally helpful to humans.
I'm not sure what would be an "incident". What would it take for a pokemon being ordered about by Team Rocket to have a witness ascribe cruelty to the pokemon in particular? That'd either suggest some extremely gruesome things have happened that the machoke's trainer clearly didn't order or that machoke are so peaceful and friendly normally that it's odd for them to even obey cruel orders. Or are Team Rocket machokes escaping (or being abandoned, maybe, if they're uncontrollable?) and then entering into the wild population where trainers run across them?
(Dark) Machamp: It is almost impossible to defend against a Machamp's four powerful arms.
This one is just another iteration of pokemon-is-dangerous.
Magikarp: Recent research has revealed the presence of dragon DNA in this species of Pokémon.
This is never referenced in any other pokedex entry! Maybe Team Rocket isn't very good at research.
(Dark) Gyarados: Normally found only in the deep ocean, it has recently been seen in shallow waters as well.
While this seems like it could be a reference to the specific events at the Lake of Rage, as I mentioned, this set predates Gold and Silver. Maybe this idea led to that?
At any rate, the idea that gyarados are naturally found very far from humans makes the fact many of their other pokedex entries talk about them as a once-in-hundreds-of-years city-leveling natural disaster make more sense than if they're found in every river. It could also explain why you can catch L40 magikarp - maybe they're really not supposed to be evolving at L20 in the first place. (...and if original gyarados are in fact specifically deep-water pokemon, and the one you find in the lake is poking out at the surface, maybe the legendary gyarados are actually a different thing entirely? Evolving differently creates a pokemon that not only lives in shallow water but prefers the very surface.)
Did you know that female praying mantises don't naturally eat the males? It turns out they only do so under extremely rare circumstances...but those circumstances were being in a brightly lit area with scientists clustered around observing their behavior, leading to us concluding that was how they always acted.
I think it's really interesting to consider if things we consider standard in the games actually only occur as a result of humans or human training influencing things, especially as later games have added alternate evolution and now alternate forms. There could be pokemon evolutions that only occur in remote areas, and there could be ones that can happen among humans but require different circumstances than are standard to pokemon training - if you don't think your eevee deserves regular cupcakes, you're not going to see many sylveon appear. Maybe there are pokemon evolutions that are locked off simply by use of pokeballs! There's certainly been a number of minor differences throughout the games between wild pokemon you can catch and that same pokemon raised from a lower level, the weirdest of which is perhaps that the move kinesis in Yellow, Gold, and Silver was exclusively found on wild-caught kadabra.
Magnemite: It is said that enough Magnemites and Magnetons gather in one place, they can create a powerful magnetic barrier.
Another one just saying what other people say, and sounding like it's an outsider and not internal Team Rocket opinion. Still, given this is in the Team Rocket set, we can assume it's referring to something they did, which then leads to the question of what did they need a powerful magnetic barrier for? Are they guarding their own areas with this so nobody can take pictures? Is this meant to justify how Saffron was somehow cut off from communication in RBY? Is this a literal wall nobody can get through that's powered by magnets?
(Dark) Magneton: The number of incidents of hackers using Magnetons to damage computer systems is steadily increasing.
Like most of the almost-certainly-meant-to-be-outsider entries, this one is more entertaining if it's Team Rocket complaining vigilante trainer-hackers keep messing with them and not someone reporting that Team Rocket's hacking other people.
Also, it seems like using magnetons on computer systems is a bit more brute force than you'd think from hackers. Maybe the main use it to wipe the system to hide evidence of whatever else happened? They're not replacing human hacker skills, they're doing a related job that makes hackers want them around.
Meowth: A popular Pokémon that earns money for its owner with its "Pay Day" ability.
This one is rather tepid. It is focused on the use this pokemon has to others, but this is pretty common for people talking about meowth. Poor meowth. The game designers really don't seem to be cat people.
(Dark) Persian: Popular with women because of its beautiful fur. The leader of the Rockets keeps one as a pet.
And this is just two existing facts. It's not even like we can connect the two into "Giovanni has this pokemon to attract women" because he shows no interest in using it for anything but petpets. Maybe the idea is these are written all the way back when his mom was in charge so it's saying that it's popular with women including the leader of Team Rocket. That'd work fine with the dratini and eevee text.
Oddish: It wanders around at night sowing its seeds to create more Oddishes.
This one isn't even really related to knowledge you'd need to catch it. I guess that you should look for them at night, but I wouldn't think oddish are so in-demand you'd need to hone your poaching skills for them. Plus in the games they live in the same area as the far rarer abra that Team Rocket is collecting by the bushel.
(Dark) Gloom: Its pollen has such a strong smell that it even confuses itself at times.
Ah, here we're back to the "dark" variants having something wrong with them. The only other reference to gloom caring about the smell is the idea it actually likes it, and other entries claim they don't stink at all unless upset. For it to be having this kind of effect would suggest what's going on here is not so much intensity as altered chemical production, or possibly that the writer is a bit off and the problem is gloom producing the chemicals nonstop and perhaps ending up deficient at times in important ones it needs to think.
(Dark) Vileplume: Perhaps because of their strong-smelling pollen, other Pokémon do not approach areas where Vileplumes live.
There is actually no other reference to vileplume smelling bad. Their pollen is super toxic across all the other pokemon entries, and certainly their inspiration smells awful, but there's another entry warning people away from smelling unknown flowers because it might be a vileplume who'll shower you in poisoned pollen and you'll die, which doesn't seem like it's possible if they've got an overpowering stench warning you away.
Perhaps all vileplume retain the stench defense of gloom but usually don't use it because their pollen is strong enough that they don't feel scared much, but the "dark" variation is constantly stressed and pumping out the same chemicals, or possibly this represents a very subtle alternate evolution that looks the same on the outside but is different internally.
Also an important question - how does anyone use a pokemon that smells so awful you can't get anywhere near it? Does Team Rocket just leave these around to create a stench wall that discourages trainers from wandering too close? Could you find Team Rocket bases by mapping out where you find unusually stinky vileplume, connecting the dots, then heading to the center of whatever shape it makes?
Ponyta: A gentle grass-eater, it will allow riders on its back. However, anyone attempting to do so must be careful not to get burned./ (Dark) Rapidash: A wild, uncontrollable Pokémon. When running, it looks like a comet streaking through the sky.
This one I think is mostly about the contrast. It does occur to me, though, that the idea of evolved pokemon being uncontrollable isn't limited to the "dark" variants here but common throughout the canon and across many pokemon evolutionary lines. This doesn't seem remarkable at first - evolved pokemon are bigger and scarier and stronger, of course they're harder to control - but it really is the opposite of how things usually go when humans start hanging out with an animal.
It also gets back to the question of whether what happens when humans train pokemon is representative of how they always work. Do wild pokemon go through a similar pattern of behavior? Is it less dramatic in the wild? Is it actually even more extreme and human-evolved pokemon, while still harder to handle, are more chill and domesticated than their wild counterparts?
Porygon: More and more people play the slots every day, trying to win a Porygon.
Can confirm I sold, like, EVERYTHING the first time around trying to get a porygon, and then went back several times to keep selling everything until I finally had enough coins.
What does this look like in-universe, though? Are there people mortgaging their houses for a porygon and, if so, why can't you buy one second-hand from someone who got one through the Game Corner and now wants cash more than they want to keep the pokemon? Or when they default on everything and all their stuff gets repossessed and put up on auction? Given it's not a particularly impressive pokemon in battling terms, you'd think demand would reduce once there's a couple in circulation and they're semi-accessible, so people must either find it impressive enough in other respects that those who have it keep it/that those who sell it aren't even a dent in the demand or else there's some Game Corner shadiness going on that ensures no one but them can sell porygon. Maybe there's some DRM-style addition and/or contract that prevents people from trading the pokeball so it can only be returned to the Game Corner? Maybe the Game Corner, fitting with its Team Rocket connection, makes sure to always be the loan sharks their gamblers use so that when repossession roles around they reclaim the porygon?
Or perhaps the ridiculously high price means that even heavy gamblers never have quite enough.
Psyduck: It is often seen holding its head in its paws, as if it were suffering from a headache./ (Dark) Golduck: When Psyducks evolve, their headaches disappear and they find themselves in possession of formidable mental powers.
Bog standard entry. I guess they were out of ways to talk about pokemon being sadistic or dangerous? Or maybe the original was something about drowning people and that got nixed.
(Dark) Raichu: Stores up electricity in its body, then suddenly releases it to surprise and shock everyone.
Now, I did learn over the course of this that including a raichu in the set was a big deal, with the card people demanding it and everyone else telling them no, which is probably related to how there's no Team Rocket pikachu card to go with this. I didn't learn why that was a big deal but I assume it has something to do with opposition to the idea of an evil pikachu, and I assume in turn that's why this entry is so tepid.
Rattata: Loves to eat walnuts, chestnuts, cheese, and milk.
Similarly tepid, though I think this is a return to entries that are about the best way to catch the pokemon. While the obvious way to look at it is that it's a rattata and no one needs to know how to poach them in large numbers, therefore mousetrap, it should be pointed out that rattata feature heavily in the teams of Team Rocket members, so they might actually want to know how to catch big batches of them.
(Dark) Raticate: A Raticate's front teeth are incredibly powerful; it can destroy a two-story house with them in 5 minutes.
And indeed, the entry for the evolved form is gushing about how great these guys are. As I recall, there's a Team Rocket guy in the middle of Mt. Moon with a L16 raticate who is all I AM THE BEST TRAINER EVER FEAR ME! so maybe he wrote this one.
Slowpoke: Although it knows how to fish, no other intelligent behavior has been detected in it.
This is also the usual insulting sort of pokedex entry slowpoke get. While presumably unrelated to the fact Team Rocket ends up hacking up slowpoke in GSC, it does sound like the sort of thing the people there would bring up when asked to justify themselves.
(Dark) Slowbro: It loves nothing better than to be left alone, and so sometimes ends up being manipulated by unscrupulous people.
This, though, is another unique bit of lore. Slowbro's normal pokedex entries talk about them being chill, so that would suggest this is another one that applies specifically to the "dark" versions evolved by Team Rocket.
But that's not what's most interesting about this. Most of these entries, as well as Team Rocket's general mission statement, are with the attitude that pokemon are (temperamental) tools. They report that these pokemon have behavior problems but show no interest in why. Here, though, the entry is talking about "manipulating" - starting from the premise that this is an intelligent creature with its own desires, then figuring out how to trick it into doing what you want.
One of the things I think is underused about Team Rocket is they're actually a rather practical team. If treating a pokemon as an individual gets things done, they'll do it...but they won't reconsider if the general rule of "pokemon are basically buggy robots that should just shut up and do what we say" is wrong. This entry suggests that slowbro are too powerful/smart for their usual methods to work or just that the "dark" variant doesn't act out in a way that's as easily aimed as, say, charizard, and so they handle them differently, but they're not going to think about why.
Also unexplained and worthy of exploration: how do they manipulate these slowbro, and to what end? How does using the "dark" slowbro work differently than the usual send-out-pokemon-to-battle thing? Does the average Team Rocket member have training in how to handle these guys, or are there a couple slowbro wranglers who know what they're doing and everyone else just tries to stay out of the way?
It also makes me think of the cyclops interpretation here, where the cyclops is what happens when an ogre gives up trying to find things to make them happy and instead tries to avoid things that make them unhappy.
Squirtle: Cute Pokémon that charms people with its innocent eyes. Loves swimming all day long.
And here we're back to ordinary entries. The first half is at least relevant - cuteness is a factor when you're stealing and reselling, looking charming and innocent could be useful to have on your own team if you're trying to convince someone you had nothing to do with all the stealing and reselling, how can you say something so mean in front of this precious baby's virgin ears?
(Dark) Wartortle: A Pokémon with a negative attitude, it hides in its shell whenever it's in a bad mood – which is often./ (Dark) Blastoise: An aggressive Pokémon that tackles anything it sees.
I like the progression here - the middle stage is clearly unhappy, but dealing with it through trying to retreat. The fully evolved pokemon has given up on defense and flight and switched to attacking whatever's there. And that's a particularly stark change given this is a turtle pokemon whose moveset reinforces it's supposed to deal with trouble with its protective shell.
Voltorb: Usually seen only in power plants, it is sometimes seen in towns, apparently using the power lines to travel.
Now, this set contains porygon, which is explicitly manmade, so perhaps we're meant to think Team Rocket is connected to these guys for similar reasons. In GSC voltorb are first stated to have some connection to the invention of pokeballs and contain components that are definitely human-manufactured - in the first gen, they're just assumed to be mimicking the appearance for camouflage reasons.
On the other hand, talking about them traveling using power lines suggests whoever was writing entries for this set wasn't very clear on what voltorb was and may have thought they were another digital pokemon or else thought they were spectacularly good at tightrope rolling. That or this is poorly worded and the idea is more that since power lines are a valid food source, when they travel away from a power plant they do so following the power lines, therefore they always end up in towns as opposed to radiating out in a random direction that only sometimes intersects with a town.
(Dark) Electrode: Some researchers hypothesize that Electrode may actually be a form of energy instead of having an actual body.
But given that we're told here they think these guys are just electricity it does seem like someone was picturing them zapping about inside of a wire.
Who are these researchers anyway? Team Rocket? Silph? Double agents working for both? Actually, perhaps a good case could be made that the sort of scientists who are disgruntled enough to sell out Silph may be the ones who are really bad scientists and their pay reflects that. If the sort of scientists who join Team Rocket largely do so because legitimate organizations insist their title is "lab tech assistant's assistant" then some researchers probably hypothesize a lot of crazy stuff.
Zubat: Lives in dark caves. Can occasionally be seen at night, when it flies in search of food.
And we end with more pokemon biology facts...
(Dark) Golbat: Sneaks up silently on its prey and attacks it from behind, sometimes killing it with one bite.
...and biology + "they're ugly so I'm just going to tell you about how they kill stuff". Kind of cool golbat got a being-nice-to-this-pokemon evolution despite all that, though. I suspect part of that was that GSC wasn't entirely clear on what the new sort of evolution was supposed to mean yet - one of the many synonyms tossed around when introduced in the second gen was loyalty , so maybe it's not so surprising they gave an evolution to a common pokemon found on the grunts of a team who'd take over a city just to beg their leader to come back and continue bossing them around? A shame that it ends up largely being the province of baby pokemon.
Anyway! In conclusion, it's always nice to examine or reexamine canon for fresh ideas. I'll certainly be using ancient deep-sea gyarados for something.