IceTop

From SmashWiki, the Super Smash Bros. wiki

IceTop is a stage which can only be found via Action Replay. Although it crashes the game when activated in Debug Mode, another hack can force it to correctly open, but it's just Icicle Mountain with no music. Some people who do not have an Action Replay simply turn off the music in Icicle Mountain, this basically gives the stage the same mechanics.