Kasain is a visibly muscular humanoid Pokemon. It is mainly pink in colour. Its crown is flat, while two sharp, triangular shapes resembling cat ears stand on either side of the top of its head. Its eyes comprise cat-like vertical pupils in front of generally light-colored sclera. It has no nose, and its thin-lipped mouth is perpetually closed. It wears dark, studded, leather-like forearm-length gloves, mirrored in style by a garter belt-like band at its waist and ankle-height footwear. Its thumbs are additionally bandaged in white. Four short spikes line the top of its back. Its shoulders, the back of its hands, belt buckle, a plate hanging in front of its crotch, both sides of its ankles and the top of its feet all bear the emblem of a skull with ears resembling its own, in varying sizes and external decoration.
Kasain's Pokedex entry is the same in all Generation X+onwards games.
This Pokemon, an "Omega Beast", is able to create explosions by setting something to detonate.