Cheat Menu(You Have to Have This to Make the Other Ones Work)
Press Left, Left, L, L, Right, Right, Right, Left, Left at the main menu.
Now you can access the cheat menu.
Switch Monsters On/Off
Hit L, C-Left, Left, R, C-Right, Right, Left, Left, Right.
Now go into the cheat menu and you can turn off the monsters.
Invincibility
Hit R seven times in a row and press left on the pad.
Now go into the cheat menu and you can turn invincibility on.
Toggle Items
Go to the main menu and press
R, C-Right, L, C-Left, Left, C-Right, Right. Now go to the cheat menu and you can toggle lots of things.