All characters and level select aka Special Mode
When starting up your Master System hold down UP and both 1 and 2 on the controller(s) that will be used to play the game until a screen saying Special Mode appears on the screen (after the title screen dissappears). You will now have one of each character and be able to choose the round and the stage that you will play, even on stage 5. Your characters will be restored at the beginning of each stage
NOTE: You will not be able to gain additional characters throughout the game.