Region (Pokémon)

Regions is a term to describe the game world in Pokémon. It is similar to a state or country.

Main Regions
The main ones have a Pokémon League which encompasses 8 official Gyms, the 4 Elite Four and a Champion, along with a system of Pokémon Centers as well as a Pokémon Professor.
 * Kanto
 * Johto
 * Hoenn
 * Sinnoh
 * Unova
 * Kalos

Spinoff Regions
These are regions that some of the spinoffs take place in though they do not have all the facilities as the main regions
 * Holon - Pokémon Trading Card Game
 * Orre - Pokémon Colosseum
 * Fiore - Pokémon Ranger
 * Almia - Pokémon Ranger: Shadows of Almia
 * Oblivia - Pokémon Ranger: Guardian Signs

Regionless Locations
These locations exist outside of normal regions and aren't specified to be in any one region.
 * Sevii Islands
 * Pokémon Island - Pokémon Snap
 * Minlet Town - Pokémon Channel
 * Pokétopia - Pokémon Battle Revolution