From Bulbapedia, the community-driven Pokémon encyclopedia.
The Ultra Beasts (Japanese: ウルトラビースト Ultra Beast) are a group of extradimensional Pokémon originating from Ultra Space. They possess power that transcends humans' understanding of the world.
Ultra Beasts infrequently appear from Ultra Wormholes in Alola. These appearances are apparently as unexpected for the Ultra Beasts as for Alolans, which tends to make them combative. They are especially drawn to people who have passed through an Ultra Wormhole, due to the residual wormhole energy on them, apparently expecting to find a wormhole they can use to return home.
There are currently seven known Ultra Beasts:
All seven Ultra Beasts share the Ability Beast Boost. While they are wild, this manifests as an aura at the start of battles that boosts one of their stats, similar to Totem Pokémon. This aura actually comes from the energy they were bathed in when they passed through an Ultra Wormhole; Wicke theorizes that they store this energy in their bodies.
Most Poké Balls have difficulty recognizing Ultra Beasts as Pokémon due to their extraterrestrial origins, impairing their ability to effectively catch them. Only the Master Ball and Beast Balls escape this impairment.
Although unconfirmed, Aether Foundation scientists hypothesized that Cosmog is also an Ultra Beast, due to its ability to create Ultra Wormholes. Necrozma's Pokédex entry also states that it is "reminiscent of the Ultra Beasts", but when it was in the wild, the International Police reported that all Ultra Beasts it had detected had been caught, and Beast Balls are not effective at catching it.
Although an extremely rare event, legends in Alola tell of fearsome Pokémon appearing from Ultra Wormholes. The legends also tell that the guardian deities would fight fiercely against them.
Years prior to the events of Pokémon Sun and Moon, Professor Mohn published a theory on Ultra Wormholes and papers describing Nihilego.
The Aether Foundation also conducted research on the Ultra Beasts. This included the development of the Beast Killer project to create a Pokémon—Type: Full—that could fight against Ultra Beasts. The Beast Killer project ended in failure, and the three known Type: Full were cryogenically frozen and their names changed to Type: Null. It also developed the Beast Ball to catch the Ultra Beasts.
The International Police have also tracked Ultra Beasts in the past and into the present under a secret division known as the UB Task Force. The UB Task Force is tasked with investigating the ecology of Ultra Beasts, protecting people from harm from them, and either safeguarding or destroying the Ultra Beasts. Ten years prior to the events of Sun and Moon, a three-person team composed of Looker, Nanu, and an unnamed Faller came to Alola to track down and destroy a Guzzlord; in the process, the Faller was killed. The International Police refer to each of the Ultra Beasts by code names.
The first reported sightings of Buzzwole, Pheromosa, Xurkitree, Kartana, and Celesteela were after the incident at Aether Paradise where Lusamine forced Cosmog to create an Ultra Wormhole and used it to travel to Ultra Space.
Base stat comparison
In the games
Pokémon Sun and Moon
During the main story, the player encounters Nihilego 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 BuzzwoleS/PheromosaM is seen emerging from a portal over Melemele Island and battling Tapu Koko. The player also encounters several Nihilego in Ultra Space after arriving with SolgaleoS/LunalaM and Lillie.
After the player becomes Champion, 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 Route 8. 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 Beast Balls have a catch rate multiplier of 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.
In the manga
In the Pokémon Adventures manga
The Ultra Beasts debuted in the Sun & Moon chapter, after Gladion loses against Sun, he contemplates about losing his chance to get to the Guardian deities that he promises to get stronger to confront them.
In other languages