The Green Missile is Luigi's forward B in Melee. It can be charged for about five seconds, to then release a kind of jump that shoots Luigi left or right. It also is his primary third jump.
The move also has a 1 out of 8 (12.5%) chance to be a spontaneous misfire, that acts like if it was fully charged, but more powerful. It's not always beneficial, however. One possibility is Luigi charging the Green Missle and aiming at an opponent. He fires, but the misfire applies and the opponent dodges. This can very often prove hard to get back onto the stage for recovery. It also leavs the Luigi exposed to edgeguarding.
Pikachu and Pichu has an attack familiar to the Green Missile called Skull Bash. The biggest difference is that they can not get the misfire.
Also see
- PimpUigi's Under the Sea video