Orochi IS kinda playable in the AES version of the game!
All you need a debug-bios. With player1 you have to fight all your way through to Orochi. Then go into the Debug-menu and enter the Dip Menu. Activate Dip 2-1 and tadaah! The 2nd player now controls Orochi.
This are his moves:
Genocide Cutter: B or D
Shoot: Quarter Circle Forward, A
Shatter low: Quarter Circle Forward, B
Shatter high: Quarter Circle Forward, C
Pillar blast: Half Circle Back, A, B, C or D
Whole-screen ray DM: Quarter Circle Backward, A or C
Suck-in DM: Upper Circle, A or C