The Ultra Beasts (Japanese: ウルトラビースト Ultra Beast) are a group of extradimensional creatures originating from Ultra Space. There are currently seven known Ultra Beasts: Nihilego (codenamed UB-01 Symbiont), Buzzwole (codenamed UB-02 Absorption), Pheromosa (codenamed UB-02 Beauty), Xurkitree (codenamed UB-03 Lighting), Celesteela (codenamed UB-04 Blade), Kartana (codenamed UB-04 Blaster), and Guzzlord (codenamed UB-05 Glutton).
Artwork depicting the Ultra Beasts
They are believed to possess great power and pose a threat to humans and normal Pokémon, especially to those who have entered an Ultra Wormhole. This is because they mistake the energy remaining on these people as a possible route back to their own dimension, and become hostile upon discovering that it is not.
All seven Ultra Beasts share the Ability Beast Boost. Wild Ultra Beasts receive a stat increase at the start of the battle like Totem Pokémon. All Poké Balls except the Beast Ball have a catch rate multiplier of 1× against Ultra Beasts; the Beast Ball has a catch rate multiplier of 5× for Ultra Beasts, whereas this multiplier is 0.1× for all other Pokémon.
According to Alolan legend, the Ultra Beasts appeared from an Ultra Wormhole and fought the guardian deities in the past. Years prior to the events of Pokémon Sun and Moon, Professor Mohn discovered both Ultra Wormholes and the Ultra Beasts.
The Aether Foundation conducted research on the Ultra Beasts, including the development of a Pokémon, Type: Null, intended to kill them. They also developed the Beast Ball to catch the Ultra Beasts, as other Poké Balls act like a standard Poké Ball because they cannot properly recognize the Ultra Beasts due to them originating from another dimension. They also hypothesized that Cosmog is an Ultra Beast from Ultra Space, due to its ability to create Ultra Wormholes.
The International Police has given each of the Ultra Beasts code names, and intends to destroy them to protect the Pokémon world. However, Anabel and Looker identify five Ultra Beasts and task the player with catching the Ultra Beasts to protect them instead. The International Police has found that the Ultra Beasts are surrounded by the same energy found in Totem Pokémon, an aura known as Beast Boost that comes from the Ultra Wormhole. Although Necrozma's Pokédex entry states that it is "reminiscent of the Ultra Beasts", the International Police has not identified it as one.