At the main menu, unlock the cheats menu by pressing Down, Up, Left, Left, A, Right, Down. Then set flag 0 and 2 to on. Press start. Next game you start, One hit will kill your opponent. This cheat is defective for the second opponent of an endurance round. And sometimes the first round of the boss Goro.
Press A, B, A, C, A, B, B at the Code of Honor screen at the beginning of the game. If you did the code correctly Scorpion should say "Get over here".
On the options menu, press Down, Up, Left, Left, A, Right, Down. This will cause an extra menu to appear.