Here's my theory on 8D.
I'm guessing that it's the same move. However, when opponents are hit, they're sort of 'Coded' with an anti-tech until they hit the ground. That way, they're safe against the loop and they don't have to change 8D to another move.
I hope that's the case. I need 8D to catch jumpy Bang players and other people who like to try and hurdle over Nirvana.