Unlock the following music tracks at the sound test menu by performing the corresponding tasks in Standard Marathon mode:

TRACK - HOW TO UNLOCK
Ancient Tetris (Tetris GB Music A) - Reach level 19
Balloon Tetris (Touch Mode Theme) - Reach level 14
Basement Tetris (Super Mario Bros. 1-2) - Reach level 3
Bowser Battle (Super Mario Bros. 1-4) - Reach level 10
CongraTetris - Beat Standard Marathon mode
Mario Tetris 3 (Super Mario Bros. 3 Overworld) - Reach level 4
Rushed Tetris - Reach level 16
Tetris Climber (Ice Climber Theme) - Reach level 15
Tetris DK (Push Mode Theme) - Reach level 13

Hold L + R + SELECT + START during game play to reset the game.

In Rushed Tetris level 17, the level's background is Devil World and the Sprite is Tamagon, the main character from Devil World, a Japanese DS game.

To unlock the "Endless" option when selecting a level in Standard Marathon mode, get more than 200 lines to complete Standard mode.