A self-destruct (abbreviated as SD) is when a character is KO'd without being hit by an opponent. This usually equates to a suicide such as jumping off the edge, but falls also count as SDs when the stage KOs someone. In time mode, self-destructs subtract one point by default from a player's score; this penalty can be changed to zero or two points. In bonus mode, the player's score is lowered by 500 points.
Killing a teammate also counts as a self-destruct.
- The character was standing on the ground, did not get hit by anything, and fell.
- The character was hit by a stage hazard and fell.
In Super Smash Bros. Brawl, however, a SD can only be attained if the KO'd character did not get hit by an opponent during the entire stock. Thusly, a character can be hit by any attack and walk off the edge, yet it does not count as an SD. Even performing a Footstool Jump without dealing damage will not make it count as an SD.