AIR

From SmashWiki, the Super Smash Bros. wiki

AIR is a Debug menu mode in Super Smash Bros. Melee. It restricts the character's jumping height. Most characters, such as Luigi, Ganondorf, Pichu, Marth, and other characters who cannot jump very high at all in regular gameplay, can barely jump at all in AIR mode, with the exception up the up B attack, or Kirby, or another high jumper.