Honestly lets see why Arc is better for your precious moogle fight:

Arc:
Ranged DD
Combos Based on Range not direction
Ability to move and shoot
Potent damage combos with right sub classes
mobility to avoid AoE
shadowbind
decent mp pools to pinch cure
excellent dps over all

all other dd
damage combos based on direction and proximity while moogles move frequently and lag leads to many missed combos
AoE magnets
poor dps due to damaged missed by moving targets
AoE dmg results in cCns with lower mp or dd stopping to cure him/herself

Cant imagine why Arcs would be choosen over any other melee dps for this fight.

On the bright side there is always Ifrit and his weapons are better. Oh wait you need Thms for quick kills on that now. Honestly deal with it people will pick a win setup over an experiment any day of the week unless that is of course they have already won enough where it doesn't matter.