Band Attacks

Here's a thought.

Replace a skill list (lets say tools for sake of imagination) with a list of your Bands (all of them).
Set up the "skills" to check if X and Y party members are in the battle and grey out the skill if they are not.
Redirect the Def command in battle to open this menu instead of Def.

Would be a tad sloppy, and I'm not sure exactly if you can check if certain members are alive and in battle, but the concept might be possible, maybe, to roughly simulate the effect anyway.