What´s your definition of "Ultimate Character" in this game?
What do you consider the strongest?
Here´s my definition:

EQUIPMENT:
>ultimate weapon<
Ziedrich
Ribbon

MATERIA:
Master Magic=Enemy Skill, Master Command=Master Summon, Double Cut=W-Summon, HP Plus=MP Plus

You could also change the Ziedrich into something that actually can
hold Materia, but personally I love that armor too much.