Hawkmouth first appeared in Super Mario Bros. 2 and reappears in Mario 3D Adventure!. In Super Mario Bros. 2 they would be found at the end of levels to teleport the player to the next level, only one of them was fought. In the Tower of Sunset Mountain, it will spit up Bob-ombs, fly toward you, and fire lasers from it's mouth.
Mario 3D Adventure
He takes 10 jumps on the head, 7 block throws, 50 fireballs, and 5 hits from a star. The Pattern: He'll spit out a Lit Bob-Omb that will follow you. Then He'll stop, jump on him! He'll Fly away from you, then fly toward you really fast. If you hit him after he stops again, he'll spit up 2 bombs and fly away from you, then he'll Fire 6 lasers from his mouth. Jump around the room or get behind him to avoid the lasers as effectively as posssible. If you hit him, he'll repeat the tactic 9 times. If you fail to hit him after he catchs his breath, he'll go crazy chasing you, doing so in a zig-zag manner. Then repeat what he did before.