I train all my ppll in ff12, but i have 2 main parties that I use:
1. Power Team
Basch(Leader)
Vaan(support)
Penelo(healer)

2.Fire Team
Balthier(Leader)
Fran(support)
Ashe(healer/black mage)

In my fire team, ihave balthier equipped with flame shot(on any gun) and fran with fiery arrows(on any bow). imake ashe use oil on the enemy, which makes the party's attack do massive damage.