I'm pretty sure any B skill is allowable for Level 6, as you need 6 As, 1 B. I'm under the impression extra Bs count as As, but I could be wrong. We have lots of girls do Back handspring or roundoff in Level 6 for their B.
I did tuck jump (A), back handspring (B), split leap (B), full turn (A), cartwheel back tuck (A and A, I think...)