Sonic Blastman Cheats for SNES
When the words "Press Start" flash four times at the Title Screen, press and hold are and L, and quickly press Start. You may now select "Very Hard" difficulty in the Options Menu.
This will allow both players to use the same character.
On Controller 2, hold L and are on the Player Selection Screen, and you'll be allowed to use the same character.
Highlight "Music Test" at the option screen, press Right or Left to select a level and press L, are, are, L, and Start. It also works on boss levels.