https://www.polygon.com/2018/5/21/17376306/pokemon-go-alolan-kanto-region-update

Pokémon Go will soon receive special new forms of several Kanto-region Pokémon. Drawn from Pokémon Sun and Pokémon Moon, Alolan variants of Pokémon like Raichu, Diglett and Meowth are going to start popping up in the mobile game.

“Sunny days are ahead! Whether your forecast calls for rain or shine, we’re celebrating all around the world by introducing some special Pokémon from the tropical Alola region to Pokémon GO,” reads a blog post from the game’s website.