Disappearing items

From SmashWiki, the Super Smash Bros. wiki

Disappearing Items is a glitch appearing in Super Smash Bros. Brawl. It allows the player to make items invisible in Training mode. To start, go to training mode and use Captain Falcon. Next, make a Smash Ball appear from the start menu. Once the Smash Ball is broken, use Captain Falcon's Final Smash on the CPU, and when the Final Smash is finished and when Captain Falcon is falling back to the stage, make items appear and they will be invisible. Picking the items up will cause them to appear.