One important aspect of a villain is their ability to survive after apparent death. And no one is better at that than Water Bear. High altitude, deep depths, no oxygen, radiation, fire, ice are all as comfy as a soft bed to Chunk. If things get too tough he just shutdowns for a bit until conditions are more to his liking. It makes him unpredictable as an ally in a fight, but you know he’ll be there for round 2.
From: Obscure Animals and Superpowers Part 2: The Villains