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In the games
A few Pokédex entries have mentioned the existence of real-world animals, mostly in Generation I.
In both Raichu's and Gastly's Pokédex entries in FireRed, Indian Elephants are mentioned.
In several of Bellsprout's Pokédex Entries, it is said that it preys on insects.
In Red, Blue, and Yellow Versions, the player makes a comment about crabs while aboard the S.S. Anne.
In Red, Blue, and Yellow, FireRed and LeafGreen Versions, a chef aboard the S.S. Anne says "Er-hem! Indeed I am le CHEF! Le main course is Eels au Barbecue!" He also speaks of a "Salad le salmon" and a beef/veal dish.
In Pokémon Ranger: Guardian Signs, barnacles can be seen in underwater areas.
In Black and White a Trainer in the Battle Subway says he is so obsessed with Pokémon that his wife is as mad as a hornet.
In the anime
A real-world cat on anime concept art Animals have been seen in the anime. They were more common in the original series as there weren't as many Pokémon species introduced at the time. A picture book based on the Pokémon anime once featured a dog walking past Ash and his friends, and a piece of concept art of the residents of Pallet Town featured a cat. Birds can also occasionally be heard in the background. Foods that contain meat products, such as hamburgers and chicken are often seen. Animal appearances have become less frequent as more Pokémon have been added to take their places.
Ash Catches a Pokémon: Misty is scared when she sees a Caterpie, and Ash tries to calm her down by reminding her that it's a Bug-type Pokémon rather than a "real" bug. Pidgeotto is seen eating a regular worm before being captured by Ash.
Challenge of the Samurai: As a pun on Caterpie, Ash is seen in a cow costume.
The Water Flowers of Cerulean City: Fish can be seen in the fish tanks inside the Gym. They have made later appearances featuring the Cerulean Gym.
Path to the Pokémon League: Misty mentions that A.J.'s ability to control Pokémon with a whip was similar to a lion tamer.
Pokémon Shipwreck:More fish can be seen swimming in the ocean near the sunken St. Anne. A fish biting Slowpoke's tail
Island of the Giant Pokémon: In the episode's Dare da?, a fish is biting Slowpoke's tail.
Tentacool & Tentacruel: Fish can be seen in the aquarium in Nastina's vision of her completed luxury hotel.
The Ghost of Maiden's Peak: A Gastly created an illusion of a mongoose in order to scare Jessie's Ekans.
The Tower of Terror: When Charmander lights up the room, a mounted deer head can be seen on the wall.
Fashion Flash: One of the signs on Scissor Street features a crab.
Holiday Hi-Jynx: Santa Claus tells Ash and his friends that he has "no reindeer" to pull his sleigh, and uses a Ponyta instead.
The Battling Eevee Brothers: In one scene, James is holding a lobster.
Attack of the Prehistoric Pokémon: In the Japanese version, Gary finds an Ammonite fossil. In the dub it is refereed to as fossilized Pokémon dung.
Case of the K-9 Capers: Meowth compares his voice to one of the chipmunks after inhaling a gas coming from a tank with a Psyduck on it.
Riddle Me This: While Ash and his friends are looking for a hotel to stay in, a picture of a tiger can be seen in one of the hotels. Furthermore, during Gary's banquet, a fish is seen sliced up.
Clefairy Tales: While Ash and his friends are falling down the sewer pipes, several skeletons of unidentified prehistoric animals are seen.
Mewtwo Strikes Back: Miranda talks to seagulls to learn the conditions of the sea.
Go West, Young Meowth: While Meowth was looking for food, he came across some fish bones. Meowth is also seen eating fried chicken.
To Master the Onix-expected: While Ash and his friends are resting, their elderly female host mentions the disappearance of her "muskrat meatballs."
A Friend Indeed: The characters are eating shrimp tempura.
Meowth's Song: Meowth mentions insects.
The Joy of Pokémon: Real fish can be seen in the moment before a young Joy falls into the water.
Meowth Rules!: Meowth is seen holding, and talking about eating Clams.
Grin to Win!: A fried chicken stand can be seen, as well as a chicken thigh, at the Sunflora festival.
Foul Weather Friends: Meowth mentions chicken feed.
Fossil Fools: A fish can be seen in statue form, being attacked by Kabutops.
Hook, Line, and Stinker: When one of Misty's catches escapes from her fishing line, Ash says that it was probably a catfish.
Trouble's Brewing: Meowth's food illusion created by the Gastly includes a fish.
The Stolen Stones!: Near the ending, Misty mentions a doghouse.
Mantine Overboard!: Various corals are visible underwater.
In the manga
In
How I Became a Pokémon Card, a cat appears in one chapter.
In
Pokémon Pocket Monsters, regular animals appear alongside Pokémon.
In
Pokémon Get da ze!, a snail appears in one chapter.
In
Pokémon Adventures, there were real-life mice, shrews and birds as Bellsprout, Weepinbell and Victreebel's prey at the Safari Zone.
In
The Electric Tale of Pikachu, the Cerulean Gym Aquarium has real-life fish and whales.
In
Pokémon Adventures, Pika is seen chasing a butterfly or a moth.
In the TCG
Numerous early Pokémon cards featured animals.
A bird perched on a Weepinbell.
A bug near a Bulbasaur.
A frog next to an Oddish.
A wasp flying near a Venonat.
A Butterfly flying near a Squirtle, and an Eevee.
A worm for Magikarp and Spearow.
A crab next to an Exeggutor
A fish near a Psyduck
Coral near Horsea, Quagsire, and Luvdisc.
Sea anemones near Wooper.
Butterflies and fish near a Slowpoke.
The shadow of what appears to be a shark is on the original Super Rod card.
Fish, or perhaps porpoises, near a Magikarp.
In books
At least three animals can be spotted in the
Let's Find Pokémon! series.
In
Let's Find Pokémon!, a dragonfly can be seen near a pond, and a worm can be seen in the beak of a Pidgey.
In
Let's Find Pokémon! 3, a Kangaskhan is eating a fish with rice.
Anime pictures:
A real-world dog featured in a picture book.
A real-world cat on anime concept art.
Ash in a cow costume.
A fish biting Slowpoke's tail.
The mongoose in
The Ghost of Maiden's Peak.
Ammonite fossil.
Meowth finds fish bones.
Kabutops and its prey.