Press Select during game play to display the menu. Then press Start on controller two to bring up a sount test menu.
Begin game play and create a saved game. Reset the Super Nintendo console and wait until the American Sammy logo is fully displayed. Then, press Up, Down, Up, Down, Select, Start on controller two before the logo disappears again. Select the Continue option, and press Select. Then press Start on controller two. The word Debug will appear next to Status to confirm correct code entry.
This code also makes you invincible.