https://www.polygon.com/2018/7/13/17569680/pokemon-go-gen-4-pokemon-piplup-turtwig-chimchar

Pokémon Go may add a new generation of Pokémon soon, based on a new piece of artwork posted to the mobile game’s official Twitter account.

The artwork was released to celebrate the two-year anniversary of Pokémon Go, and highlights many of the additions to the game over the past year: Alolan Pokémon, the ability to trade Pokémon and send gifts, Professor Willow and Mew, the mythical Pokémon players could battle as part of the field research game mechanic.