I find the easiest way to beat any regular boss in the game (NOT bosses like nemesis/penance, where you basically NEED max 255 agility and doing 99,999 damage per regular hit to get in 20 hits, summon an aeon as a sacraficial lamb when nemesis/penance hits, hit 20 times again, rinse, repeat)
is as follows:
For every stat point Yuna gets, her aeons get 4. So what you do is warp her to say, Aurons section on the sphere grid, pump her strength like mad, and then use any aeon you have that comes with break damage limit, or even for seymour, your most powerful aeon, and just whack away with super-pumped str for 9999 each hit. Easy as pie.
The first time I fought -Final Boss- (not spoiling with the name of it. and i mean final boss, not the token battle that you can't lose at the end of the game.) for example, i had Anima with 255 str, so, it was Pain - form 2 - Pain, dead.
