Super Mario Bros. Deluxe/DX
COLOR Game Boy Only

Extra lives:
Note: This trick only works on a new game. Select the "Toy Box" option at the main menu, then select "Fortune Teller". Keep looking at the cards until five lives are earned. Return to the main menu and choose to play the "Original" levels. Start a new game to begin with ten lives instead of five. 

Unlimited lives:
Immediately hold A when a life is lost, and keep the button held until the map appears.

Unlimited continues:
Hold A at the game over screen.

You vs. Boo bonus levels:
Score at least 100,000 points during game play. Then, select Boo as a character at the title screen.

Level select:
Successfully complete the first quest.

View fireworks:
Successfully complete a level with a time that ends in a 1, 3, or 6.

Reveal Yoshi egg locations in challenge mode:
Locate one Yoshi egg, then go to the toy box and select Yoshi's head.

Japanese version of Super Mario Brothers 2
aka: Super Mario Bros - The Lost Levels:
Accumulate 300,000 points in the Classic game without losing All lives, and without saving and restarting the game. A new "Super Mario Bros. For Super Players" game will be unlocked.

Play as Luigi:
Press Select at the Map Screen to toggle between Mario and Luigi.