For anyone hoping the Ultra Beasts will get cool new abilities to go with their flavor text in the next game, don't. They already get them as level zero attacks.

>Nihilego uses spicy neurotoxins that boost/manipulate a target's stats to protect the symbiont
Power Split
Guard Split

>Buzzwole stabs fools with its stinger nose and drains their fluids to dramatically boost its attack power
Fell Stinger
Leech Life

>Pheromosa is the fastest thing around, and shits pheromones that confuse foes and reduces their will to fight
Quiver Dance
Lunge
(I'll admit this one's a stretch. Phero doesn't have anything to confuse stuff, and QD doesn't so much reduce the foe's will to fight as it boosts defense to reduce damage.)

>Xurkitree plants itself to draw electricity from the dirt and boost its own power
Tail Glow ("Glowing" pokemon)
Electric Terrain

>Celesteela sprays flammable gas to fly
Air Slash (technically, only the dex says it burns stuff with the gas, and that's second hand from witnesses. Wicke just says its flammable, and the animation just shows it being heated.)

>Kartana is folded one million times and can cut through anything
Sacred Sword (ignores opponent's stat changes)

>Guzzlord eats everything, converts it all into energy, and never poops
Stockpile
Swallow
doesn't Spit Up