Green Shell glitch
The Green Shell glitch is a glitch in Super Smash Bros. involving the usage of a rapid-hitting attack on a pile of Green Shells. As the attack hits the Green Shells, they will hit each other in an infinite loop, causing the attacker to be locked in hitlag until the Green Shells all vanish. Should there be an opponent in the mix, they may take over 999% damage from the sequence.
The Mario Tornado is the most well-known move that causes the glitch, with the Super Jump Punch, Screw Attack, along with Luigi's taunt and the third hit of Link's neutral attack being other methods of invoking it. The typical setup involves placing the opponent on one side of the player and using training mode's menu screen to add four Green Shells on the other side, then using the attack to hit both the opponent and the pile.
The glitch has no practical use; there are no situations in regular gameplay with a stack of two or more shells, and a competent opponent will simply SDI out of the attack.
The glitch can also be performed with Red Shells, which give slightly different and more unpredictable results such as instantly dealing around 800% damage and knocking both characters away.
It cannot be performed in PAL versions of Super Smash Bros.