After complete all seven special stages, return to the main menu and press Up, L, Down, R, Right, Left.
Start a new game and successfully complete all three Acts of Toy Kingdom Zone to unlock Amy.
Start a new game and successfully complete all three Acts of Cyber Track Zone to unlock Cream.
Start a new game and successfully complete all three Acts of Sunset Hill Zone to unlock Knuckles.
Successfully complete the game. You do not need all the Chaos Emeralds. The "Sound Test" option will appear just above "Delete Game Data" in the options menu.
Successfully completed the game. Do not have all Emeralds but have a Golden Ring in all stages (Act 1, 2, 3 and vs. Boss).
At the "Press Start" screen, press R. In the upper right corner, the game will display the color setting that you are currently on. Press R again to change the color settings. There are three color setting: "Game Boy Advance", "Game Boy Advance SP", and "Game Boy Player". The color settings optimize the color for the system that you are using.
Have Tails as your partner. If you missed an elevated platform or area during a level, use Tails' Tag action on the ground. About 95% of the time you will be able to reach what you fell off from. Note: This can also be done to access certain areas of the Act faster.
After collecting all the Emeralds, play the "Final Boss level" with Sonic as the leader and anyone else as your partner. Once you change to Super Sonic, Dr. Eggman will become your partner in order to help you defeat the final Boss.
Play as Knuckles and Tails. Have Knuckles as your lead and when you face Eggman, use Knuckles' glide. Having Tails as your partner will give Knuckles more elevation on his glide, allowing you to hit Eggman's weak spot without any elevation help from the hands or the balls that fly around.
In Zone 2, Sunset Hill, the music that plays is a remix of Green Hill Zone from Sonic The Hedgehog.