||You can unlock a Debug Mode that gives you access to all weapons in the game, as well as testing most features the game has to offer. To unlock it, you have to go to the Stage Select screen, and press the Jump button on each boss mugshot in reverse alphabetic order (from Z to A). Press the Jump button in this exact order:
Dr. Witless, Weather, Scissor, Rock, Paper, Muffin, Mail, Icecream, Fisher.
Weather Man's mugshot will be replaced with Emperor Man. Pick that stage and Debug Mode will begin.