ok i just beat him today. heres what i did. 1st i leveled up sora to 84. now then if you dont know where to find him hes in radiant garden (original name of hollow bastion) hell ask you what cloud is doing etc. then hell say something like "i wonder if itll change its mind 1 i beat you" the battle will begin. 1st of all he has 3 attack phases. 1 phase hell use a quick attack where hell say "moon shine down" or something like that. the minute you see the triangle button come up hit it. next and this is the key to winning have these abilities equipped before hand (beserk charge, once more, and trinity limit) the rest is up to you. after he does the attack unleash trinity limit and dont stop hitting buttons when it goes to the triangle hit triangle. hell keep up this attack til about 5 bars of life are gone but trust me youll be way ahead of that when you unleash enough trinities. anyway the 2nd phase is kinda like the 1st except now hell add a few more attacks 1 is where hell put dark orbs surronding you knock them away trust me. the 2nd attack is where he says " decend heartless angel" this attack will knock your hp down to 1 and mp down to 0. now here comes the tricky part. use an elixir that will get you back up to snuff and enable you to unleash another round of trinity limit. eventually hell do it again and just do the same. after about 5 bars his final phase begins. get ready this is where it gets really tough. hell get quicker and have a new ability called meteor. hell still use heartless angel and ocasionally use the dark orbs keep using elixirs if you can and trinity limit. eventually youll win and thats it. but you cant kill him so you have to talk to cloud hes in the marketplace. now go back to sephiroth and a battle will go on between him and cloud but i cant tell you the outcome youll just have to fight sephiroth.