Easiest way to beat any level...After Balthier

Balthier + Luso + Ramza + White Mage/Time Mage + Bard = Death

Balthier is by far the cheapest guy in the game, with his speed being ridiculously high. Just give him all the best speed gear you have (Ninja Gear) and have Luso and Ramza just Tailwind him, while the Time mage does haste and the Bard Rousing Melody. Unstoppable...

It's especially fun to max out Balthier's Magic Attack and cast the Faith Status on him, then use Barrage with a Magic gun at an enemy.

Barraging with a Chaos Blade is fun as well...

I just wish Barrage worked with Duel Wield.