To knock down your opponent in 1 hit, go to the Z-Store and then to the Bonus Settings. Once you are in the Bonus Setting, click on "Instant Death." Then go to Tournament, and pick your character. Once you are fighting, be careful, not to get hit, cause you will die instantly. But the same thing will happen to your opponent, hit them once and they will die, not to mention that you will get a perfect every time you fight.