From Shoryuken Wiki!
- Unlock Final M. Bison - Defeat the game as M. Bison and then hold Start when you select him in a new game. (Note: Final M. Bison always uses Shadowloo-ISM)
- Fight Shin Akuma in Final Battle mode - After selecting your character, mode, and ISM; hold L and R before the VS screen comes up.
- Select Shin Akuma - Hold Start when selecting regular Akuma.