I dont think its specifically mentioned if there are real animals in the Pokemon world, its a real mystery.
Some Pokedex entries I've found:
Raichu: "Its electric charges can reach even 100,000 volts. Careless contact can cause even an Indian elephant to faint."
Gastly: "A being that exists as a thin gas. It can topple an Indian elephant by enveloping the prey in two seconds."
Really makes you wonder why they chose Indian Elephants.
Lol Im not, but you get my point.