Pokémon World is the name given to the pocket dimension in the metaverse that includes a pocket version of Earth known as Pokémon Planet, where the events of the Pokémon franchise take place. Humans live on it alongside Pokémon in a similar manner to the relationship between humans and animals in real, whether as pets or as wild animals.
Known regions on Pokémon Planet include Kanto, Johto, Hoenn, Sinnoh, Unova, Kalos, Alola, Galar, Paldea, Ransei, Ferrum, Orre, Fiore, Almia, Pasio, Oblivia and Lental.
Theories
There have been numerous fan theories about the existence of Pokémon World and its connection to the universe. Although it is unlikely, it may be that humans have inhabited another planet somewhere else in the galaxy, in addition to Earth. Another suggestion put forward by fans is that the story may take place in a parallel dimension that also includes humans.
It is also assumed that it could be set sometime in the future, mostly because of the fact that people use enhanced technology such as Poké Balls, teleportation (in the PCs), and mechas (Team Rocket).
Animals have been mentioned many times, such as in Pokémon Shipwreck, when Ash saw a fish when looking out the window. In one episode, a Pidgey could be seen eating a worm. Also, when Ash caught his Caterpie, Misty mentioned that she hated bugs; however she could be just referring to Bug-type Pokémon. But solid proof of common animals existing 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.
The entry for Raichu in Red and FireRed states that its electricity is so strong that it can kill an Indian elephant. However, the English versions of its entry in Red and FireRed, as well as in Sun, only say that it can knock out an Indian elephant instead. In Legends Arceus, Copperajah, a Pokémon based on an Indian elephant, is mentioned instead.
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. Arcanine's entry states that this is a Pokémon from China. Also, in the movie Mewtwo Strikes Back, Ash said Vikings mostly live in Minnesota (which references the Minnesota Vikings sports team). In one of Magikarp's Pokédex entries, it states that they can jump over the Eiffel tower. Also, there have been episodes that referenced Las Vegas and Chinese food.