He also appears in I Wanna Be the Boshy as an obstacle in World 2, and as an unlockable character in the same world.
How hazardous is he? Edit
It depends on where in particular the player encounters him. He appears twice in the world. The first time, he tries to inhale you, and will jump when the player jumps. If the player is inhaled, Kirby will jump into the Spike pit behind him, killing the player. The second time, he has grown to an enormous size, making him too big to jump over. Walk back to the previous room and wait for him to pass by.