What are they for? I see them throughout the final battles from braskas final aeon to Yu Yevon, but what do they do, and is their any benefit to attacking them?

They heal the bosses, remove negative status effects, and sometimes cast minor spells.

When do they do this though, because If never seen them do anything except freeze when I attack them?

They do it whenever they get a turn.

hmm, the battles dont usually last that long with me, usually one or two hit kills, so i guess they dont get a chance to do anything.

Thanks

I may be wrong, but I seem to remember attacking Braska's final aeon with zombie attack, so that when the Yu Pagodas healed him, they hurt him.

But they would have also healed the zombie status...