In Pokemon Ultra Sun and Ultra Moon, there are these legendary Pokemon that comes from another dimension called Ultra Beasts.
Aspiring Champions looking to catch them will have to spend time scouring around the world and search for these elusive beasts. But then, there are certain requirements on how to catch them:
Poipole
Location: Ultra Megalopolis
After defeating the Ultra Necrozma, you will be getting Poipole as a reward by Ultra Recon Squad. This is the first Ultra Beast that you will get in the game.
Nihilego
Location: Ultra Deep Sea
Availability: Ultra Sun and Ultra Moon
Once you are able to explore the Ultra Space, you will find Nihelgo in the Ultra Deep Sea under the White Wormhole.
Buzzwhole
Location: Ultra Jungle
Availability: Ultra Sun only
Under the White Wormhole once again, find Buzzwole in the Ultra Jungle. Just follow the vines upwards to the tallest true and find Buzzwole when the volcano errupts.
Pheromosa
Location: Ultra Desert
Availability: Ultra Sun and Ultra Moon
In the Ultra Desert under the White Wormhole, find Pheromosa. You must first solve multiple strength puzzles using Machamp Shove. Once you complete the challenge, you will get Pheromosa.
Xurkitree
Location: Ultra Plant
Availability: Ultra Sun and Ultra Moon
Find the Ultra Plan in the White Wormhole to catch Xurkitree. You will find that the area is shaped like a Xurkitree with lots of them in the background. As you walk through the area, a lightning will strike repeatedly. Reach the top to find Xurkitree and a lightning will struck it, causing it to attack you.
Celesteela
Location: Ultra Crater
Availability: Ultra Moon only
In the White Wormhole, find the Ultra Crater to catch Celesteela. This area will have lots of small craters to explore. At the end of it, you will find Celesteela.
Kartana
Location: Ultra Forest
Availability: Ultra Sun only
Ultra Forest is the area where you will find Kartana. You must first find Ultra Forest in the White Wormhole to catch Kartana. Find Kartana starting at a rock to battle and catch it.
Guzzlord
Location: Ultra Ruin
Availability: Ultra Sun and Ultra Moon
Once you are able to explore Ultra Space, go to the White Wormhole and find the Ultra Ruin. When you are in the area, find the man in a protective gear who mentions that everyone has evacuated the world because of the “Mr. Glutton”. Explore through the Hau’oli City and in the end, you will find Guzzlord eating everyone it can.
Stakataka / Blacephalon
Location: Poni Grove
As soon as you become the Champion, you will get summon by the Ultra Recon Squad to come help out. Once you reach the Poni Grove, there are multiple Ultra Beasts causing destruction. The Ultra Recon Squad will give you Beast Balls to capture them.
If you are playing Ultra Sun, you will be able to get Blacephalon
If you are playing Ultra Moon, you will get Stakataka.