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Mawile is weird, you can use the horns as a battering ram for something like Iron Head, biting moves AND special moves, but they would require a different animation for all of them. I think PBR actually did this and gave Mawile an animation where it lifted the horns up and smashed them on the opponent, on top of the obvious biting animation.
All it really needs is a punching one and it'd be perfect, lord knows GF would never go through the trouble of making it spit fire out of both jaws if they can't be assed to do it for Blastoise.