Zero Two is much more than the final boss of Kirby 64, he is the ruler of dark matter and a fallen angel. He is also the recarnation of Zero. The bandage on his head is where Zero's eye blew up. You defeat him with Ribbon and her shard gun. If you hold L or R on the N64 controller, you and Ribbon will spin around. He is only seen if you collect all of the crystal shards.