So Finally, I Have Tried Them

[ljkkjlcm9]

I haven't been able to get that far in the game though, I'm stuck in the battle where Locke is fighting alongside the moogle army, and I'm having a lot of trouble taking down all those enemies.

That's your problem right there. You only need to kill the leader at the bottom of the screen.
My suggestion: Either
1) Use the party with Locke to run directly to the boss and kill him.
2) Use the party with Mog, fight once to learn a dance, then proceed to the boss and kill him.(use Mog's new Dance)

either way, I suggest at least fighting once with Mog here just to get the dance.

THE JACKAL