These codes are to be used on the main menu (when Game Start & Options) appear. NTSC-U/PAL does not have a proper Level Select code, instead relying on a Level Control control code. Instructions on how both codes work are listed bellow.

For NTSC-U/PAL copies:

=LEVEL CONTROL #1=

B+A+B+Y+↓+→+A+L+↓ (BABYSEALS)

• After inserting the code, a sound effect will play. Select any level in a world and once you enter gameplay, hold the Left Trigger. While doing so, press Up to go to the next level, and down to go to the previous.

=LEVEL CONTROL #2=

↓+→+X+Y+←+→+A+↓+→+L (SEXYWEASELS)

• After inserting the code, a sound effect will play. Select any level in a world and once you enter gameplay, hold the Left Trigger. While doing so, press Up to go to the next level, and down to go to the previous.

For NTSC-J copies:

=LEVEL SELECT=

L+A+B+Z+A+X (LABZAX)

-After inserting this code, a traditional level select will be pulled up. Beating a level from this level select will put you on the following level.

=LEVEL CONTROL #1=

→+A+↓+→+A+↓+→+Y (EASEASY)

=LEVEL CONTROL #2=

B+↑+Z+Z+B+A+B+Y (BUZZBABY)

• After inserting the code, a sound effect will play. Select any level in a world and once you enter gameplay, hold the Left Trigger. While doing so, press Up to go to the next level, and down to go to the previous. Note that using this on a boss stage will put you on the bonus round.

Most of these codes were discovered by memory_fallen on Twitter.