Not a lot of Billy activity. Sad times. I have however finally started using his Hyperdrive combos, settling with the easiest possible one in the corner:
Jump in C, cr.C (or cr.Bx3), Activate Hyper Drive, s.C, B SRK, HCF+C, QCB+C, HCF+A, QCB+C, HCF+A, QCB+C, and Neo max. Does about 730-750.
Not bad. Can't seem to crack 800 damage in a way that's easy to do though. His EX Super is a pretty sweet chip kill if you have them cornered.