I've noticed that the GFs have levels of compatibility with certain characters, Shiva is 100% compatible with Squall, while Ifrit isn't at all. I'm guessing that while as the GFs are leveling up and learning things, to stick them with characters that they are most compatible with and/or leaving them with those characters to get the best results.

Also, how beatable, for lack of better wordage, is the game without all the GFs? I'm having a hell of a time getting Diablos at this point. (I'm at the end of Disc1) I didn't think I had enough power to defeat him earlier and now he's all but KOing me before I've had a chance to do anything. Switching characters around, playing with junctioning, etc, doesn't help, so far.

Thanks in advance!