leon, cloud, yuffie, tifa....
need i say more?
alright, first off-you should be at level 99 with a defense and strength of high 60's or low 70's
second off, unequip all ablites that relate to combos on ground and in air (slide dash, combo plus etc...) to where your combo is only two swings or hits or whatever...you need negative combo for that.
make sure you have explosion and the finish move to where you slide foward and attack. thats important.
third, have plenty of high potions and ETHERS! (important)
of course have the second chance and once more abilities to ensure health and when low on HP just glide around and dodge their attacks until your MP is restored to cure yourself
Get Curaga by beating 100 acre wood
Ultima Weapon for MP Hastega is a BIG PLUS!
Level up your forms to get new abilites (glide, ariel dodge etc...)
thats all, hope this helps!