You asshats Reflect does damage back to Sephiroth.AND HE IS NOT CLOUD'S HEARTLESS.You need to have the retailiate or/and Aerial Recovery equipped.Slapshot is good to have to seeing as to you can combine Retailiate with slapshot when you get knock into the air.Take little damage when possible but if you see an attack that can lead to a opening for damage,if you gaurding against it will break your opening just take that hit and attack instantly afterward,you could use counterattack if you have learned the skill already.Quick run is very useful too.You learn quick run from leveling up you Wisdom form.When Seph makes those black balls all over the place Use reflect when they come at you.Best to have Sephiroth inside the reflect ball when you do it.THE MORE DAMAGE IS DEALT BY HOW CLOSE YOUR ENEMY IS TO THE REFLECT BALL.BEING INSIDE OF THE REFLECT FIELD=MEGA DAMAGE POSSIBLY A WHOLE BAR AND A HALF FOR SEPHIROTH AND DEATH TO ALMOST ANY NORMAL ENEMY!When he uses the flaming pillars...RUN LIKE HELL.They are easy to get away from...but if he has taken enough damage it will suck you in no matter where you are on screen.And if you get inside of it don't try to him.REFLECT YOUR ASS OFF UNTIL YOUR FREE.And just because you see reflect a lot during my explaination doesn't mean you won't be fighting with your keyblade a lot more.I was on level 73 when I beat him.That means nothing nor does the Keyblade have to be Ultima Weapon.I was using Rumbling rose so my combo finisher(Explosion which strength is measured by your magic,I had finished my wisdom lv ups already)would be amplified.Explosion does an assload of damage and even more with high magic.And a trick to lvl up fast,once you get the Gullwing blade if you finished Pride rock go to the top of the cliff through the Loin's den at Pride rock.There are Hundreds of tiny yellow heartless floating around.The ability for the Gullwing is exp boost,make sure you have the magic skill magnet and your health is low enough(in red with that annoying sound going} for you to activate the effect.If you have learn exp boost naturally already equip it too so this can be done faster.Run aroung and cast Magnet on the yellow heartless,take donald and goofy's healing support skills and items off so you never g3t out of the red.Magnet draws them in and if you have good enough magic it should kill them too.Otherwise just use magnet, and attack what it draws in and repeat.Don't worry about magic running out to often plenty of magic balls will drop so you can regain it.Once you clear all the heartless out you should be at least 5-7 levels higher.DO NOT HEAL YOURSELF IF YOU WANT TO KEEP GOING.To make all those heartless reapper to do it again you must go 2 rooms away and come back(this applies in any part of the game)that mean leave the top of the cliff,then leave the rock to go as if you were heading to the fields,go to the field and come right back to the top the cliff where the heartless reside.I did this and I was on lv.99 in 45 mins, just keep doing it until you get to the level you want.Also if you every want full drive at anytime,use your drive form(any one of them) and while transformed go to the save point and leave the world.Then when go back(or any other place you desire to go) and you'll have max drive.