Equip Lionheart or Oblivion(Ultima Weapon if u have it)Just start off by attacking.He will disappear after u hit him 1-4 times. When he lose 2 bars he will do a move called Sin Harvest. LOCK ONTO HIM AND SUPERGLIDE TO HIM AND ATTACK HIM. If u do not u just lost the battle. If u get him keep attacking him normaly until he does it again and do this same strategy. He will teleport everywhere trying to hit u. Then he will go to the middle and do his ultimate move.Stay near the edge to avoid some damage. You should get hit about 3 times. Use Curaga to heal urself(Use it anytime u need to)Attack him normaly. Avoid being behind him because lil black gravity balls will follow him and give u a fairly good amount of damage.Attack him normaly then back off. Do this over and over again.He will be dead.(Ive beat him with only a Kingdom Key equiped to me and it was very easy...He is not hard to beat....If u avoid his Sin Harvest and heal with Curaga when u need to u should have no problem)