Pheromosa did not originate from fanon, and the information on this page may not be entirely accurate to their canon. You may read more about this subject in the context of their canon on the following wiki(s):
Pheromosa, known in Japanese as フェローチェ (Pheroache), is a Bug/Fighting-typePokémon, and one of the seven Ultra Beasts. It is also known as UB-02 Beauty (Japanese: UB02 BEAUTY). It isn't the only Ultra Beast that has the UB-02 serial, as it shares this with Buzzwole.
Pheromosa resembles a anthropomorphic, feminine cockroach. It has a thin build and is mostly white. It has a segmented body, having five segments divide its torso. Pheromosa has a semi-circular head and a long, thin neck, and has narrow, white eyes with purple iris and blue pupils. Pheromosa has long, thin legs, suited for running and kicking. Its joints have golden pads, and its feet consist of two, twig-like structures, resembling high heels. Furthermore, it has two large antennae that almost reach to the feet, and long, translucent hair, which makes it resemble the shell of a cockroach.
The lithe, elegant body Pheromosa has is capable of extreme feats of acceleration, allowing it to twitch any part of its body at up to 120 mph. Pheromosa also displays considerable reluctance to touching anything, as if the Pokémon world is unclean.