The way you're describing is a little gay (and wont translate well for the male audience members), but for dramatic presence, Iceman could be getting overwhelmed by Pyro's flames, and by intensifying his cold power to save himself, he inadvertantly changes into ice. He then realizes this ability, and ice-slides circles around Pyro for a knock out (via a hail of snowballs).... That was a little lame too, but you get the idea.
I think what would work is a body suit like Johnny Storm wore in the Fanstastic Four movie. Only black, with a giant X patch woven on it. It's kind of remenicent of the body suit Iceman wore back in the mid nineties...