Nobody can fly.
Naruto cannot use Kyuubi, but starts off in sage mode (without ma and pa).
Ichigo cannot use his hollow, but can go vizard.
This is regular Sephiroth and Kefka, not their other forms.
Halibel and Stark begin in thir released states.
All bleach characters can obviously be seen/ interacted with.
Battle takes place at Hueco Mundo (because Aizen's on vacation).