Luigi (SSB)/Dash attack
Luigi runs forward and throws seven punches, only six of which have hitboxes. Each hit does 2% and this can do up to 12% if all are hit. It is rather useless competitively, due to it's high end lag, low combo potential, and how hard it is to hit due to Luigi's slow dashing speed. It is easy to punish, and is rarely used.
Originally, there would have been two more hitboxes, one for the seventh punch, and one for Luigi's head with notable knockback, but due to a developer oversight these two hitboxes do not appear in the regular game.