Tetris Attack

Select Rivals

To access the rivals in the two-player vs mode, press the L and R buttons simultaneously on both controllers at the character select screen. While holding these bottons, press A on controller two.

Extra Hard Game

Choose the one-player vs mode. On the set level screen, highlight the hard level. While holding up and the L button press A.

Play As Other Characters

Choose the one-player vs mode. After you complete a stage, press and hold X and Y during the cinema scene. A player select screen will appear before the next match begins.

Passwords

Have a ball with these handy-dandy passwords:
StagePassword
1None
2STDJ7YJ!
3SNGD7Y9!
4SHD87Y7!
5S2DF7Y!!
6SQD57YD!
7SJDL7Y2!
8S1RL7YN!
9SC?L7BC!
10SB?L7BJ!
11SY?L7B9!
12S6?L7B7!