At the title screen, enter one of the following for the desired effect, a sound will be heard upon correct entry.

Code	Effect
A 5 times, B, A 5 times, then hold down Select for 5 seconds.	Developer profile 2.
A, B, Right, Left, Right, Left, Down, Down, Up, Up, then hold down Select for 5 seconds.	Developer profile Gon.
B 5 times, A, B 5 times, then hold down Select for 5 seconds.	Developer profile 1.
Left, Left, Right, Right, Up, Down, A, A, B.	Invincible and Stage Select.
Left, Left, Right, Right, Up, Down, A, A.	Invincible.
Left, Left, Right, Right, Up, Down, A, B.	Stage Select.
Up, Left, Down, Right, Up, Left, Down, Right, B, A.	Sound Test.