Level Select
Using the second controller, you can enter a cheat that will transport you to the level of your choosing. Go to the game's main menu and press "A," "B," "C," "Left," "Right," "A," "B," "C," "Left," "Right," "A," "B," "C," "Left" and "Right" to access the level selection feature.
Lives
The second controller also lets players acquire 70 additional lives in the game. Press "C," "B," "A," "Right," "Left," "C," "B," "A," "Right," "Left," "C," "B," "A," "Right" and "Left" to begin your game with the advantage.
Hidden Endings
Viewing all of the game's endings is easier if you use a cheat instead of beating the game multiple times. Move to the underground area of the Junkyard stage. Go to the wall that appears before you reach the door with mounted weapons. Scale the wall to find the character that offers an arena fight with three new bosses. Defeat the bosses to see the endings.
All Weapons
The Japanese version of the game provides a cheat to acquire all of the weapons in the game. Pause the game and enter "Up," "Up," "Down," "Down," "A," "Up," "Up," "Down," "Down," "B," "Up," "Up," "Down," "Down" and "C" to acquire your new arsenal.