https://www.gamespot.com/articles/pokemon-go-raids-get-new-bosses/1100-6454707/

Pokemon Go has received a number of big updates over the past year, but one of the most notable changes was the introduction of Raid Battles. Beginning this past June, players could team up with friends to battle against powerful boss Pokemon at Gyms. Aside from appearances by new Legendary Pokemon, however, Raids have featured the same list of bosses since the feature first rolled out back in summer--until now.

Pokemon Go developer Niantic has refreshed the list of boss Pokemon players can encounter in Raid Battles (via Eurogamer). Surprisingly, Niantic didn't advertise the change in advance of its implementation; instead, the developer quietly rolled it out over the past weekend.