First, some basic info about them. The Ultra Beasts are a group of extradimensional Pokémon from Ultra Space. They possess power that humans don't really understand. Currently there are seven known Ultra Beasts, all with the ability Beast Boost. Beast Boost raises the pokémon's most proficient stat when it knocks out a pokémon.
Now, lets look at them individually.
UB-01 Symbiont, Nihilego
Nihilego is a Rock/Poison type, and the first known Ultra Beast. It is called the Parasite pokémon. Nihilego is a parasitic organism, capable of injecting a neurotoxin that subtly alters the thoughts and actions of any human or Pokémon that becomes its host. Spoopy af. It has a stat total of 570, like the other Ultra Beasts.
Pokémon Sun entry: One of several mysterious Ultra Beasts. People on the street report observing those infested by it suddenly becoming violent.
Pokémon Moon entry: One of the Ultra Beasts. It's unclear whether this pokémon is sentient or not, but sometimes it can be observed behaving like a young girl.
UB-02 Absorption, Buzzwole
Buzzwole is a Bug/Fighting type. It is called the Swollen pokémon. Buzzwole is an Ultra Beast that resembles a large, red, anthropomorphic mosquito. It has bulging muscles that appear to be made out of sacs that are filled with a red fluid that has small white bubbles rising in it. These muscles also have white ''veins'' running through them and are said to be stronger than steel.
Pokémon Sun entry: This Ultra Beast appeared from another world. It shows off its body but whether that display is a boast or a threat remains unclear
Pokémon Moon entry: A mysterious life-form called an Ultra Beast. Witnesses saw it pulverize a dump truck with a single punch.
I don't really like Buzzwole that much, i just think it looks dumb and I don't get the idea behind all the flexing.
UB-02 Beauty, Pheromosa
Pheromosa is also a Bug/Fighting type, and it's called the Lissome pokémon. Pheromosa's lithe, elegant body is capable of sudden feats of acceleration, able to twitch its limbs at an estimated 120 mph or 200 km/h instantaneously, a speed previously unseen in the world.
Pokémon Sun entry: One of the dangerous Ultra Beasts, it has been spotted running across the land at terrific speeds.
Pokémon Moon entry: One of the Ultra Beasts. It refuses to touch anything, perhaps because it senses some uncleanness in this world.
So it's basically this thing
that hates germs
I like it quite a bit though.
UB-03 Lightning, Xurkitree
Xurkitree is a pure Electric type, and is known as the Glowing pokémon Because this Ultra Beast reportedly raided a power plant, it is speculated to sustain itself with electricity. This is supported by observations that it will "plug" its limbs and tail into the ground when it is low on energy, entering a tree-like state to absorb electricity from the earth. Witnesses claim that its entire body crackles with astonishing electrical power.
Pokémon Sun entry: One of the mysterious life-forms known as Ultra Beasts. Astonishing electric shocks emanate from its entire body, according to witnesses.
Pokémon Moon entry: It appeared from the Ultra Wormhole. It raided a power plant, so people think it energizes itself with electricity.
It's a bunch of wires and zipties running around raiding power plants. I love it.
UB-04 Blaster, Celesteela
Celesteela is a Steel/Flying type and known as the Launch pokémon. According to the Aether Foundation, its most distinctive feature is the energy that it stores within itself: a flammable gas that it can shoot from its two huge arms. This is mostly used to propel itself in flight and for battle, but it is thought to have sufficient power and lift to even fly into space. Despite being a Steel type, Celesteela's body is plantlike and can absorb nutrients from the soil.
Pokémon Sun entry: It appeared from the Ultra Wormhole. Witnesses observed it flying across the sky at high speed.
Pokémon Moon entry: One kind of Ultra Beast. Witnesses have seen it burn down a forest by expelling gas from its two arms.
I don't think i really like this bamboo-flamethrower-rocketfuel-thing
It's okay though, i don't hate it
UB-04 Blade, Kartana
Kartana is a Grass/Steel Pokémon, known as the Drawn Sword pokémon. Despite its small size compared to the other Ultra Beasts, Kartana is extremely dangerous, as every edge of its body is incredibly sharp. It is able to cut down a gigantic steel tower with one stroke of the blades on its arms, and any opponents that try to attack it will be similarly cut apart.
Pokémon Sun entry: This Ultra Beast came from the Ultra Wormhole. It seems not to attack enemies on its own, but its sharp body is a dangerous weapon in itself.
Pokémon Moon entry: One of the Ultra Beast life-forms, it was observed cutting down a gigantic steel tower with one stroke of its blade.
It's a cool origami sword pokémon. I like it
UB-05 Glutton, Guzzlord
Guzzlord is a Dark/Dragon type, and is known as the Junkivore pokémon. Guzzlord's tongue moves in a wave-like motion that pulls food towards its mouth. Its texture is said to feel like hard rubber. According to reports, this Pokémon has gobbled up mountains and swallowed buildings whole and will eat absolutely anything else it can reach, including the very land and sea.
Pokémon Sun entry: It has gobbled mountains and swallowed whole buildings, according to reports. It's one of the Ultra Beasts.
Pokémon Moon entry:A dangerous Ultra Beast, it appears to be eating constantly, but for some reason its droppings have never been found.
This is probably my least favorite Ultra Beast, but i don't hate it. I just slightly dislike it.