Environmental Adaptation

[Omni]

This sounds like the kind of thing which could come under a role-playing fodder power. As long as you note that his resistance to heat or cold is only environmental and has its limitations (so he won't be any more resistant to elemental attacks such as a fire or frost beam from a prime, and there are certain hazards that he wouldn't be able to resist). As Desco said, we consider water breathing to be a role-playing fodder power. Same as summoning scuba equipment or re-breather. We wouldn't allow it to help you in a fight, but we don't mind you adding it as flavour to your character if they have an alien physiology or some such. There is no cost for role-playing fodder powers.