At the title screen, enter the following codes to unlock the corresponding cheat. If you entered the cheats correctly, you’ll hear a confirming sound.

All Characters
Press Down, Down, Down, Down, Down, R, R.

All Levels
Press Up, Down, Up, Down, L, R, L, R.

All Upgrades
Press Up, Right, Down, Left, R, L, L, L.

Infinite Lives
Press Right, Right, Right, Up, Up, L, L.