I have the american domestic realese and the only max things I had where: Aurons can due 9999 damage, Yuna/lulu have holy, Lulu has flare/ ultima. Here was how I went into battle: (the characters I used)
Tidus: about 6500 hp 114 mp with strength+5% zombietouch and peircing
Auron: about 7500 hp 146 mp Peircing, counterattack
Lulu: 2180 hp 91 mp sensor magic+10% amgic +5%
Yuna: 3180 hp 214 mp half mp cost magic +10%

I used no summons and cast hastega on my party, when lulu lost all her mp (or had about 37 i think) I switched with Yuna (she had half mp cost) I used her holyto eat the hell out of it. Only two of my characters got knocked out and it lasted only a couple of minutes.