In X-Men: The Last Stand, grade system of mutants are used for the first time. Iceman and Pyro are level 3, Professor Charles Xavier and Magneto are level 4, Jean/Phoenix is the only one level 5 mutant. And Wolverine, I dont know his level, maybe level 3, almost level 4? But his trousers, obviously is level 6, because even Phoenix cant destroy it.

However, the trousers is not unique, Superman’s red briefs is bulletproof, and Bruce Banner, he has the biggest pants all over the world!