

Coach was never really a superhero, per se, although he does have abilities beyond those of mortal man (sorry, couldn't resist). His powers are a bit less obtrusive though. He's an power dampener. Which makes him uniquely suited to coach a school full of budding superheroes. By using his powers, he makes students push that little bit extra, or use powers in a way they wouldn't have normally though of, helping them discover their powers, and develop new ones. This also would explain how the school can exist without getting blown up by errant powers, since it doesn't have a true 'danger room'.
The extent of the Coach's power-dampening has not been fully codified. However, it is safe to say that he can exert a moderate amount of control. He can dampen one power while allowing others to function, or restrict the level of a power without shutting it off completely. He can affect several (or even dozens of) students at once, though it is reasonable to assume he cannot dampen the powers of someone who is not within his field of vision. However, the exact "area of effect" has been left undefined. While he cannot use his powers like a scalpel, it is fair to say he can use them like a rusty knife: with a fair degree of specificity, accuracy and finesse.
Examples of his dampening field have been:
- Allowing an entire SJS football team to play a normal, unpowered team (with only minimal accusations of cheating);
- Enabling a student to use their blasts, but not their nova;
- Sapping the energy from a student who was using a nova to prevent the action;
- Suppressing magical energy, alien physics, and super-science as well as mutations.
Thanks to Oby for the original writeup of Coach Waters, and to Wachabe for the original Waters concept.