At the Battle Beast order form screen, enter YOYOYO and enter the codes:
AOFREOIO: grants access to all the bonus doors.
EATEE: beast morphing off.
EHRTRR: autoflying in bonus rooms.
ERHNE: makes you fight all opponents.
ERHYHRLY: weakens the insidious Toadman.
ITIHFO: two out of three bouts.
OAOAEIOA: autoflying in the lab.
OFOVH: doubles time limit in bonus rooms.
OIVNNFOF: tadpole attacks in the lab.
ORUFO: invincibility in bonus rooms.