Perfect shot
If you are losing after about six minutes of playing, when there is a circle with a "4" on it, step on it. It will move to a different location. Keep doing this until it has stopped moving to a different location and then hold Circle to shoot. It will be a perfect shot. If you shoot a ball by holding Circle, there will be a color around the ball. If it is red, it indicates a bad shot. If it is yellow, it is a good shot. If it is green, it indicates a perfect shot.
Winning the Slam Dunk Showdown easily
Select an excellent dunker (for example, Tracy McGrady, Dwyane Wade, Kobe Bryant, etc.), then choose a bad dunker. Set your controller icon to no one, then start the game. Do not put your controller on someone until one person has 100 to 1,000 points to the goal. Then, set the controller icon on that specific player and finish them off.