Penance

[Kefka]

Ok, i've finally decided to go and defeat all the dark aeon's, the bad thing is Penance is really destroying my Party, i can manage to kill off both arm's but then he quickly kill's off my party with a round of attack's. Here is my best Party i'm using:

Tidus:
HP: 49,974
Attack: 194
Defence: 212
M-Defence: 123
M- Attack: 162

Wakka:
HP: 43,543
Attack: 231
Defence: 156
M-Defence: 167
M-Attack: 91

Yuna:
HP: 51,978
Attack: 102
Defence: 174
M-Defence: 221
M-Attack: 255

So, any tip's? I try to focus on getting a character's certain attributes higher than other's, since my Yuna only uses summon's and magic, i tend not to focus on her attack.