http://www.newsweek.com/pokemon-go-raid-boss-update-shiny-shinx-1173747

The Gen 4 update in Pokémon Go has brought a ton of changes to the popular mobile game. Not only were more than 20 Pokémon introduced from the Sinnoh Region, and what hatches from eggs was also changed, but the Raid Bosses have shifted around to have a Gen 4 feel.

Hours after the Gen 4 update went into effect, the Raids in Pokémon Go were changed, with the first tier bosses being all from the Sinnoh Region. There are even reports of trainers finding a Shiny Shinx after defeating it.