https://www.theverge.com/2018/10/16/17982022/pokemon-go-gen-4-date-announced-niantic-sinnoh

Pokémon Go players will be able to considerably expand their pokédexes this week, as Niantic has confirmed the arrival of the fourth generation of pokémon. This generation first appeared in the Nintendo DS games Pokémon Diamond, Pearl, and Platinum, and hail from the Hokkaido-influenced Sinnoh region.

As with the third generation, Niantic will be rolling out the new pokémon in waves rather than all at once. The company says it’ll also be announcing new features and expansion to pokémon storage soon. Meanwhile, a handful of generation 3 pokémon — and even one from generation 2 — are yet to be added to the game, mostly because of unique characteristics that Niantic has to figure out how to integrate.