>>38096355Pheromosa's "ultra beastness" is just everything that's opposite to what you'd expect from a roach monster design. This is what the devs stated was the design philosophy behind the UBs, using Buzzwole's muscularity as an example (you'd expect a mosquito to be thin and frail).
E.g. Roaches are famous for being hard to kill, survivalist creatures, Pheromosa's got the durability of a wet paper bag.