Deucalion
Firebringer
To be honest, William could defeat Eric by just using his portals and nothing else. Your resistance won't stop being divided in half by a portal. Your strength won't matter because you won't be fast enough to catch me teleporting via portals. Your hot/cold thingy doesn't affect me either.
If you're really skilled with that pistol, then I may have to use my time perception ability. Probably not the time stop part tho.
But this is to be expected, William is the StuCo Contractor Vice-President for a reason. He wouldn't be there if just anyone could challenge and beat him.
He does have weaknesses though. He has next to no physical strengths other than what his powers grant him. He'd likely be completely defeated after getting hit by anything. Not to mention his powers can sometimes be quite draining, so if you can survive his attacks and outlast him then you'd probably win that way. Or hey, perhaps you can surprise him and catch him off guard with a surprise attack?
I mean, fair enough as far as a council member goes, that's reasonable, but have you considered making a character more in line with what seems to be the average student power level? For when we leave the school for beast-slaying and stuff, I mean. It's not exactly fun being overshadowed all the time, if you catch my drift.