Gamecube Console Cheats (GameCube)

When you turn the machine on you will see a square bouncing down to
  form the G. If you hold A during this sequence as the square is
  bouncing down it will spin which looks very cool.

  Alternate Boot

  To hear a different sound when the console loads hold the z button
  down once you turn the console on and as the sqaure bounces down you
  will hear the noises of kids.

  


  

  Memory Card Help

  On the memory card screen you are given 3 options.

  And then once click you are given 2 and the bottom one is the highlighted
  one.

  After you click one of these 3 options the 2 options given are yes
  being the top and bottom being no.

  Please take note the bottom option out of the 3 given is DELETE which
  will permanently delete your data if selected.

  If you own 2 memory cards you can use the middle option is copy which
  will copy your data to your other memory card.

  I haven't tried the top option yet.

  And on super monkey ball under options (after the click start screen)

  The bottom option and the option under that option should be auto
  save.
  

Before you turn on the console hold the z button then turn on the
  console it should make a different noise.

  

  

If you have 4 controllers (and 5 hands) this cheat will work. 
  Its like the duck sound.  Before you turn the Gamecube on hold
  down Z on each controller, then turn the system on(with your 5th hand
  of course ).  You will be greeted by a ninja yell.