Instructions
Break the Backboard
Select "Classic" or "Remix" mode from the main menu at the start.
Land a slam dunk by running toward the basket and pressing the "Shoot" button when you are close. You can greatly improve your chance of landing a dunk by holding the "Turbo" button while running. A dunk performed in this fashion is a turbo dunk and usually has a flashier animation than a normal dunk.
Progress through the game normally until the last two minutes of the fourth quarter, performing as many successful dunks as you can along the way.
Perform a turbo dunk in the last two minutes of the game; you have a very high chance of breaking the backboard. If it doesn't break right away, keep landing turbo dunks until it does.
Iron Will Trophy
Run toward the basket while your partner has the ball.
Jump toward the basket and press the "Pass" button when you are in mid jump. If you time it right, your partner will pass you the ball as you are just above the basket.
Land the dunk to complete an alley oop. If you shatter the backboard, you will receive the Iron Will trophy. Normal rules apply to breaking the backboard during this maneuver. The trophy is only available during Classic and Remix mode.
Backboard Smash Mode
Enter Backboard Smash mode from the main menu.
Select a character who is highly rated for dunking ability.
Land slam dunks exclusively. During this mode, regular shots give you no benefit. Each dunk removes a small portion of the backboard's life meter, represented by a green bar.
Continue dunking until your opponent's backboard's life meter is empty. The last dunk will shatter the backboard and win the match.