The other two characters will want Comrade, not Ally, but I'm sure that's what you were trying to say. Also, if you're gonna try the Don Tonberry thing, equip a weapon that doesn't have Break Damage Limit on the character that is going to be attacking, to make sure that you don't kill it too quickly.

And yeah, I've just finished the sphere grid with all the characters. I'm now in the process of clearing the lower value nodes and replacing them with +4's in order to stat-max and fight the last few Dark Aeons...