Debug Menu
At the title screen, press A, B, Up, Down, Left, Right, Start. A menu with difficulty level, lives count, weapon toggle, boss select, game type, level select, and (non-functional) sound test options will appear. This code only works in the Japanese version.
Hidden Options
At the title screen, press A, B, X, Y, Start. A menu with difficulty level, lives count, bonus point toggle, and sound test options will appear. This code only works in the Japanese version.