Other than the obvious battle script stuff.. there's a few things worthy or note in them.
The first Big Bang's damage can be altered dramatically, since the magic power of it doesn't reset after countering against magic/summons. This is fixed in FF4A. Strangely enough, the attack doesn't seem to be evadable at all even with the lowered spell multiplier... but is at least minimized to a 1x spell multiplier hit. It's worth looking into further.
Apparently the HP refill is very obvious if you don't see a counter vs magic/summons midway through attacks... it seems that the HP check takes precedent over the counter check.
We have EVEN MORE themes now, but some old ones are gone...