At the main options screen,press X,Y,Z,Z,Y,X,Y,Z,Y.
First pause the game and then press Z, X, X, Z, Y, Z, Y, X, Y. You should now have all weapons.
Hold X + Y + Z + L + R at the main menu screen until the phrase ''Info Mode: On'' appears.
Pause game play and press Z,Z,X,X,Y,X,Y,X Z at the skill level selection screen. A new ''No Monster'' skill level mode will appear and become selectable.
Pause the game and press X, Z(2), X, Y, X, Y, Z, Y.
Pause the game, press Y,Y,Z,Z,X,X,Y,X,Z.