Enter the level select cheat. At the sound test menu in the level select screen, play the following tracks: 4, 1, 2 and then 6. Now simply select any level. All the chaos emeralds are now in your possesion, meaning you can become Super Sonic by collecting at least 50 rings and jumping, and you do not have to worry about doing any of the bonus rounds.
At the title screen, enter the following code: Up, C, down, C, left, C, right, C, then hold A+C and press the start button. When the game starts, their should be lots of numbers which mess up the score and time words in the top left corner of the screen. B changed Sonic into an object, C will plant the object onto the screen and A will change the object. Press B again to change back to Sonic.
Enable the level select code, and at the level select screen there is a sound test option. Play tracks 1, 9, 9, 2, 1, 1, 2, and then 4. Select the level you want to play, but hold down A then press start. Screen coordinates will appear instead of a score and the number of objects displayed will appear instead of the time remaining. Press B to change Sonic into an object, press C to plant an object on the screen and press A to cycle through available objects.
NOTE: This code does not work properly when playing the game as Tails alone.
Chose Sonic 2 and go to options, then play sounds 19, 65, 09, 17 in that order. then press start and hold down A. When you get to the title scrren press staat and the level select will be there!!!
At the title screen in Sonic 1, press Up, Down, Left, and Right. You should hear a sound confirming it. Then press and hold A and press Start
At the title screen, enter the following code: Up, up, up, down, down, down then up. This changes Tails' name to Miles. Enter the code again to change the name back to what it was before.