Shadow Luigi is the brother of Shadow Mario. He has appeared in several games, and looks extremely identical to his brother, Shadow Mario, but is taller, skinnier, and has an L on his hat instead of an M.
Shadow Luigi appeared in Mario Kart: Double Dash 2 as an unlockable character. His partner was Shadow Mario.
In this game, he is one of the Shadow Bros. He is the Koopatron- a robotic Koopa created by Bowser, while Bowser Jr. is Shadow Mario.
Shadow Mario and Luigi were originally planned to be in this game, but due to the fact that there were already too many medium-weight drivers, they were rejected to even out the numbers
The Mysterious Brother
In New Super Mario Bros. Sunshine, he is a troublemaker working alongside Bowser Jr., who is in his Shadow Mario disguise. They are causing trouble around Isle Delfino, and its surrounding islands. It is up to Mario and Luigi to stop them!