REGISTER TO REMOVE ADS
did u read the guidebook? it tells you how to get by the rounds w/ the bosses in it (round 25: cloud & tifa, etc.) if ur @ lvl 99 u gotta be doing something wrong (no offense) .. what might help is when you can use ur Drives mainly go for master and final b/c in valor you can only heal w/ items and in wisdom you cant use physical attacks. try to only cure when you're about to die and stock yourself w/ a lot of items along w/ Donald and Goofy. Heres one other tip: use a couple Limits..they can help out a lot.
For the final rounds, you should you the Ultima Weapon and Trinty Limit. After that, I just glide away from my oppenents and wait for my MP to charge and do it again. The only time this doesn't work is on Round 48 because of those stupid Cresedendo heartless. I hate those things!