Ultra Beast/Games/SM

During the main story, the player encounters at Aether Paradise during their first meeting with Aether President Lusamine, when it emerges from a spontaneously appearing Ultra Wormhole. During the player's confrontation with Lusamine after she captures Nebby, Lusamine uses Nebby's power to open Ultra Wormholes across the Alola region, bringing Ultra Beasts into the region; Nihilego is seen emerging from the portal near Lusamine, while / is seen emerging from a portal over Melemele Island and battling. The player also encounters several in Ultra Space after arriving with / and Lillie.

After the player becomes, some Ultra Beasts remain at large around Alola. The player receives a card from a stranger directing them to visit the motel on Akala Island's. When they enter the guest room, they will find Looker and Anabel, who invite the player to join the International Police's UB Task Force and protect the Ultra Beasts currently loose in Alola. Upon accepting, the player begins a series of missions to capture the Ultra Beasts, spanning all four of Alola's islands, each time based out of the island's motel (or the restaurant on Poni Island). In some missions, there are multiple of the same species of Ultra Beast to be captured, and in some missions they may be found at either of two locations. If the player flees from or defeats an Ultra Beast, it remains in the area and the player will still be able to find it again immediately (either at the same place or at the alternate location, if applicable). When the player is in an area where there are Ultra Beasts during a mission, the music changes from the area's normal score.

All Poké Balls except Master Balls and s have a catch rate multiplier of 0.1× against Ultra Beasts; the Beast Ball has a catch rate multiplier of 5× for Ultra Beasts. If a Beast Ball is used against any other type of Pokémon, its catch rate multiplier is 0.1×.

Unlike regular Pokémon, the Pokédex will not record Ultra Beasts as seen; it will only register them when they are caught. If an Ultra Beast is not in the Pokédex, its name will show as ??? in battle.