Like the other Ultra Beasts, Pheromosa hails from an alternate dimension, arriving in the Alola Region after some mysterious wormholes have opened up around the islands. These beasts were being studied by the Aether Foundation, and it was discovered that Ultra Beasts are essentially Pokémon that hail from this strange dimension. Pheromosa is most notable for it's incredible speed. It refuses to touch anything, perhaps because it senses some uncleanness in this world.
Type Resistances: Pheromosa's dual Bug and Fighting type combination allows it to only take half damage from Bug, Dark, Fighting, Grass, and Ground-type attacks.
Beast Boost: The signature ability of the Ultra Beasts. The move raises the Pokémon's highest stat by one stage upon knocking out an opposing Pokémon (for example, if Pheromosa's highest stat is Speed and it knocks out a Pokémon, it's speed will be raised by one stage. Same applies if it's Attack or Special Attack is it's highest stat).
Type Weaknesses: Pheromosa's dual Bug and Fighting type combination means it recieves double damage from Fairy, Fire, and Psychic-type attacks, and quadruple damage from Flying-type attacks.
Glass Cannon: While Pheromosa's insane Speed combined with it's high Attack and Special Attack stats makes it a force to be reckoned with, it's defensive stats are pitiful and even a resisted attack can OHKO it if it's strong enough.