For your interest, Wario himself is the hottest Wario character of course.
(Yes, I know Waluigi is hotter, but he's not a Wario character, mind you. And besides, that would be just plain unfair, since no-one can outsexy the great Waluigi anyway. It's just not done to compare anyone with Waluigi in this aspect. Waluigi FTW! )