To coincide with global Pokémon GO Fest celebrations, the team behind Pokémon GO has announced that Ultra Beasts will make their presence known in several locations worldwide during in-game events. More specifically, players should look out for Ultra Beasts in Berlin, Seattle, and Sapporo, as part of special research tasks within the game.
As per the game’s promotional teaser, “Ultra Beasts are mysterious Pokémon originating from Ultra Space. One such Ultra Beast, Nihilego, made its first appearance during Pokémon GO Fest, but it appears that others may soon emerge…”
Special items including “Beast Balls” will also be available during this time. Additionally, the following will be available for players who purchased tickets for the event (during event hours on the corresponding ticket day):
Players can currently purchase tickets to Pokemon GO fest events, although supplies will be limited. More recently, the Pokemon GO team has also announced that Hisuian Pokemon will be available during the “Hisuian Discoveries” event, which will include Hisuian Growlithe, Hisuian Qwilfish, and Hisuian Sneasel, to name a few.
Source: Pokemon Go Live