Best customised abilities?

[Peter_20]

In my opinion, this is the best overall equipment:

Break Damage Limit
Triple Overdrive
Evade & Counter
Str+20

Auto-Potion
Auto-Protect
Auto-Haste
Auto-Phoenix

You never really need Ribbon, because any ambushing status-loving enemies (Great Malboro, etc) can be avoided by having Auron in the party with his Masamune, and thus you can have him Flee at once in order to avoid the status attack; sometimes Provoke works as well.
And Break HP Limit, well, same thing there: any >9998 attack on your whole party can be predicted, avoided, countered with Auto-Life, and so on.