Sega Mega Collection Cheats (GameCube)

Sonic #1

  
Debug Mode
  
Go to the Sonic 1 title screen and
  press Up, X, Down, X, Left, X, Right, Up, X, Down, X, Left, X, Right,
  X.  Now HOLD B and press Start.  Now when the game starts
  press A to go to debug mode
  
Pick Level & Sound Test
  
Go to the Sonic 1 title screen and
  press Up, Down, Left, Right.  Now HOLD B to pick a level &
  get sound test

Sonic #2

  
Pick level
  
Go to the Sonic 2 Sound Test screen
  and play sounds 19, 65, 09, 17.  Now HOLD X and press
  START.  Now on the title screen HOLD B and press START
  
Debug Mode
  
Go to the Sonic 2 Sound Test screen
  and play sounds 01, 09, 09, 02, 01, 01, 02, 04.  Now at the sound
  test screen HOLD B and pick a level and Start
  
Be Super Sonic
  
After doing the Pick Level code
  above go to the Sound test screen and play sounds 04, 01, 02,
  06.  Now collect 50 rings and jump to be Super Sonic

Sonic #3

  
Pick Level
  
As you hear SEGA spoken BUT before
  the main menu appears press Up, Up, Down, Up, Up,Up.  Then at the
  title screen press UP to get Stage select and Sound Test
  
Debug Mode
  
Go to the Stage Select screen and
  HOLD B and pick a level and start
  
Get Extra Stage
  
After doing the Pick Level code
  above go to the Sound test screen and play sounds 01, 03, 05,
  07.  Highlight the Special Stage 2 and HOLD B and press START