I've heard many people say that Trubbish is confirmed a cat, because of it featuring in apparently cat-themed official artwork and merchandise by Kino Takahashi. However, this is pure speculation. There is nothing indicating that every Pokemon here is meant to be a cat. In fact, the only mention of "cat" at all is on a tweet mentioning Cat Day.
You know what does count as confirmation of a real-world species analogue? Directly addressing the Pokemon as that species.
If you didn't know, TPC runs a Cocomelon clone called "Pokemon Kids TV", and one of the things it uploads is music videos of nursery rhymes featuring Pokemon. Since nursery rhymes come from the real world, they'll no doubt mention real-world animals, and TPC needs to pick Pokemon to animate to represent these animals. What follows shortly is a tier list of each of those picks I could find and how much it surprised me. I tried to be reasonable in my assumptions that the speaker is referring to the Pokemon currently on screen. I also skipped generic categories like "bird", "fish" and "lizard".
Small aside, the nursery rhymes often get translated from English to Japanese and vice-versa. The convention seems to be to keep the animal references in the original language but change all references to Pokemon in translation. Thus, "Over in the Meadow" is about real animals in English, but Pokemon in Japanese, and "Usagi, Usagi" is about, well, rabbits (translator's note: usagi means rabbit) in Japanese, but Pokemon in English. There are some exceptions, like "Old MacDonald Had a Farm", which might just already have a widely adopted Japanese translation, and "Oh Where, Oh Where Has My Little Dog Gone", which changes "dog" to various Pokemon despite having its original title. I'm only looking at the original versions.
Pretty obvious or well-known
Squirtle is a turtle (うらしまたろう, うさぎとかめ)
Rattata is a rat (Over in the Meadow)
Butterfree is a butterfly (ちょうちょう)
Pikachu is a mouse (Hickory Dickory Dock)
Raichu and Pichu are mice (Over in the Meadow)
Vulpix is a fox (こぎつね)
Meowth is a kitten (Three Little Kittens)
Psyduck and Golduck are ducks (Old MacDonald Had a Farm)
Poliwag, Poliwhirl, Poliwrath, and Politoed are frogs (かえるのがっしょう)
Ponyta is a horse (Old MacDonald Had a Farm)
Magikarp is a carp (ふるさと)
Spinarak is a spider (Itsy Bitsy Spider)
Mareep is a lamb (Mary Had a Little Lamb)
Azumarill is a rabbit (うさぎ うさぎ)
Teddiursa is a bear (The Bear Went Over the Mountain)
Miltank is a cow (Old MacDonald Had a Farm)
Torchic is a chick (Old MacDonald Had a Farm)
Seedot is an acorn (どんぐりころころ)
Spoink and Grumpig are pigs (Old MacDonald Had a Farm)
Barboach is a loach (どんぐりころころ)
Kricketot and Kricketune are crickets (むしのこえ)
Combee and Vespiquen are bees (ぶんぶんぶん, Over in the Meadow)
Pachirisu is a squirrel (ゆりかごのうた)
Cherrim is a cherry blossom (ちょうちょう)
Buneary is a rabbit (うさぎとかめ, ふるさと, うさぎ うさぎ)
Croagunk and Toxicroak are frogs (かえるのがっしょう)
Pidove is a pigeon (はとぽっぽ)
Joltik and Galvantula are spiders (Itsy Bitsy Spider, Over in the Meadow)
Fennekin is a fox (こぎつね)
Froakie, Frogadier, and Greninja are frogs (かえるのがっしょう)
Bunnelby is a rabbit (うさぎ うさぎ)
Litten is a kitten (Three Little Kittens)
Dewpider is a spider (Itsy Bitsy Spider)
Stufful is a bear (The Bear Went Over the Mountain)
Grookey is a monkey (Five Little Monkeys)
Scorbunny is a rabbit (うさぎ うさぎ)
Corvisquire is a crow (ゆうやけこやけ)
Corviknight is a crow (Over in the Meadow)
Nickit is a fox (こぎつね)
Wooloo and Dubwool are sheep (Over in the Meadow)
Polteageist is a teapot (I'm a Little Teapot)
Sprigatito is a kitten (Three Little Kittens)
Quaxly and Quaxwell are ducks (Five Little Ducks)
Tarountula is a spider (Itsy Bitsy Spider)
Unexpected, but I agree
Bulbasaur is a frog (かえるのがっしょう)
Raticate is a muskrat (Over in the Meadow)
Azurill is a rabbit (うさぎ うさぎ)
Fletchling and Talonflame are robins (Over in the Meadow)
Goomy and Goodra are snails (かたつむり)
At least somewhere in the ballpark
Pidgey is a pigeon (はとぽっぽ)
Fearow and possibly Dodrio are turkeys (Old MacDonald Had a Farm)
Sneasel is a cat (ゆき)
Plusle and Minun are rabbits (うさぎ うさぎ)
Glaceon is a dog (ゆき)
Froakie and Greninja are toads (Over in the Meadow)
Oricorio is a canary (ゆりかごのうた)
Mudbray is a horse (Old MacDonald Had a Farm, Jingle Bells)
Bounsweet is a loquat (ゆりかごのうた)
Rookidee is a crow (ゆうやけこやけ, Over in the Meadow)
Completely out of left field
Psyduck is a snail (かたつむり)
Spoink is a rabbit (うさぎ うさぎ)
Froakie is a rabbit (うさぎ うさぎ)
Oricorio is both a cuckoo and an owl (しずかなこはん)
Dondozo and Tatsugiri are snails (かたつむり)
You know what does count as confirmation of a real-world species analogue? Directly addressing the Pokemon as that species.
If you didn't know, TPC runs a Cocomelon clone called "Pokemon Kids TV", and one of the things it uploads is music videos of nursery rhymes featuring Pokemon. Since nursery rhymes come from the real world, they'll no doubt mention real-world animals, and TPC needs to pick Pokemon to animate to represent these animals. What follows shortly is a tier list of each of those picks I could find and how much it surprised me. I tried to be reasonable in my assumptions that the speaker is referring to the Pokemon currently on screen. I also skipped generic categories like "bird", "fish" and "lizard".
Small aside, the nursery rhymes often get translated from English to Japanese and vice-versa. The convention seems to be to keep the animal references in the original language but change all references to Pokemon in translation. Thus, "Over in the Meadow" is about real animals in English, but Pokemon in Japanese, and "Usagi, Usagi" is about, well, rabbits (translator's note: usagi means rabbit) in Japanese, but Pokemon in English. There are some exceptions, like "Old MacDonald Had a Farm", which might just already have a widely adopted Japanese translation, and "Oh Where, Oh Where Has My Little Dog Gone", which changes "dog" to various Pokemon despite having its original title. I'm only looking at the original versions.
Pretty obvious or well-known
Squirtle is a turtle (うらしまたろう, うさぎとかめ)
Rattata is a rat (Over in the Meadow)
Butterfree is a butterfly (ちょうちょう)
Pikachu is a mouse (Hickory Dickory Dock)
Raichu and Pichu are mice (Over in the Meadow)
Vulpix is a fox (こぎつね)
Meowth is a kitten (Three Little Kittens)
Psyduck and Golduck are ducks (Old MacDonald Had a Farm)
Poliwag, Poliwhirl, Poliwrath, and Politoed are frogs (かえるのがっしょう)
Ponyta is a horse (Old MacDonald Had a Farm)
Magikarp is a carp (ふるさと)
Spinarak is a spider (Itsy Bitsy Spider)
Mareep is a lamb (Mary Had a Little Lamb)
Azumarill is a rabbit (うさぎ うさぎ)
Teddiursa is a bear (The Bear Went Over the Mountain)
Miltank is a cow (Old MacDonald Had a Farm)
Torchic is a chick (Old MacDonald Had a Farm)
Seedot is an acorn (どんぐりころころ)
Spoink and Grumpig are pigs (Old MacDonald Had a Farm)
Barboach is a loach (どんぐりころころ)
Kricketot and Kricketune are crickets (むしのこえ)
Combee and Vespiquen are bees (ぶんぶんぶん, Over in the Meadow)
Pachirisu is a squirrel (ゆりかごのうた)
Cherrim is a cherry blossom (ちょうちょう)
Buneary is a rabbit (うさぎとかめ, ふるさと, うさぎ うさぎ)
Croagunk and Toxicroak are frogs (かえるのがっしょう)
Pidove is a pigeon (はとぽっぽ)
Joltik and Galvantula are spiders (Itsy Bitsy Spider, Over in the Meadow)
Fennekin is a fox (こぎつね)
Froakie, Frogadier, and Greninja are frogs (かえるのがっしょう)
Bunnelby is a rabbit (うさぎ うさぎ)
Litten is a kitten (Three Little Kittens)
Dewpider is a spider (Itsy Bitsy Spider)
Stufful is a bear (The Bear Went Over the Mountain)
Grookey is a monkey (Five Little Monkeys)
Scorbunny is a rabbit (うさぎ うさぎ)
Corvisquire is a crow (ゆうやけこやけ)
Corviknight is a crow (Over in the Meadow)
Nickit is a fox (こぎつね)
Wooloo and Dubwool are sheep (Over in the Meadow)
Polteageist is a teapot (I'm a Little Teapot)
Sprigatito is a kitten (Three Little Kittens)
Quaxly and Quaxwell are ducks (Five Little Ducks)
Tarountula is a spider (Itsy Bitsy Spider)
Unexpected, but I agree
Bulbasaur is a frog (かえるのがっしょう)
Raticate is a muskrat (Over in the Meadow)
Azurill is a rabbit (うさぎ うさぎ)
Fletchling and Talonflame are robins (Over in the Meadow)
Goomy and Goodra are snails (かたつむり)
At least somewhere in the ballpark
Pidgey is a pigeon (はとぽっぽ)
Fearow and possibly Dodrio are turkeys (Old MacDonald Had a Farm)
Sneasel is a cat (ゆき)
Plusle and Minun are rabbits (うさぎ うさぎ)
Glaceon is a dog (ゆき)
Froakie and Greninja are toads (Over in the Meadow)
Oricorio is a canary (ゆりかごのうた)
Mudbray is a horse (Old MacDonald Had a Farm, Jingle Bells)
Bounsweet is a loquat (ゆりかごのうた)
Rookidee is a crow (ゆうやけこやけ, Over in the Meadow)
Completely out of left field
Psyduck is a snail (かたつむり)
Spoink is a rabbit (うさぎ うさぎ)
Froakie is a rabbit (うさぎ うさぎ)
Oricorio is both a cuckoo and an owl (しずかなこはん)
Dondozo and Tatsugiri are snails (かたつむり)