Pokémon World

We can assume that the Pokémon anime, games and other stories take place on Earth, or some Earth-like world. Humans live on this planet alongside Pokémon as a human-animal relationship. Although it is unlikely, it may be that humans have inhabited another planet somewhere else in the galaxy. Another suggestion put foward by fans it that the story may take place in a parallel universe.

It is also assumed that it is set some time in the future, due to the fact that people use inhanced technology such as Poké Balls, teleportation (in the PC's), and mechas (Team Rocket).

Animals have been mentioned many times such as when Ash caught his Caterpie, Misty mentioned that she hated bugs. She could be just referring to Bug-type Pokémon. But solid proof of common animals exsisting is the Pokédex entry for Gastly:

'''A being that exists as a thin gas. It can topple an Indian elephant by enveloping the prey in two seconds.'''

Surely, if there were no Earth animals on this planet then the Pokédex would surely refer to Indian Donphan perhaps instead of elephant.

Locations from earth have been referenced despite not appearing in the games such as Mount Everest in one of Delibird's Pokédex entries and Hollywood from Meowth's backstory in the anime. Also in the movie: Mewtwo Strikes back, Ash said viking mostly live in Minnesota.

Some fans think that the poke world is set on the future Earth.There may be another continent west of Africa in the atlantic ocean, the Pokemon Continent which includes the regions of Kanto ,Jotho, Hoenn, Sinnoh ,Unova, Fiore, Almia ,etc..the Pokemon species exist only on this continent,nowhere else. This may be real as Lt. Surge is believed to be from the US Army.