When Godzilla ripped off part of Jellar, it quickly grew into Kastam-Jellar. Helping its brother, it rushed into combat and tackled Godzilla on sight. It fought bravely, but in the end its life was short lived, as it was crushed and beaten by both Godzilla and Zone Fighter. Kastam-Jellar finally met its end when the two warriors finished it and its brother off with Godzilla's Atomic Breath and Zone's Proton Beam.
Being a newborn, it has no developed abilities and attacks besides body-slamming an enemy during combat.