Luigi is generally viewed as the lesser known of the Mario Brothers who occasionally makes a cameo appearance in Mario games and rarely stars in games himself. Luigi often serves as the second player character in Mario games. However, this is not because Luigi is less capable or less popular. It is because Luigi has got more important shit to do than save his brother from turtles and dragons all the time. In fact, these is some question as to whether Mario's "enemies" actually exist or if Mario is just on a perminant acid trip. Luigi only appears in Mario games after Mario dies because Luigi is only there to bail Mario's ass out of difficult situations. Luigi actually served 10 years as a green beret in the United States Army (thus the green hat) and is capable of beating the living shit out of Mario or his foes at any given moment, but likes to see his brother sweat a little. The reason that Luigi's army status is not widely known is because most of his work has been classified, but Luigi has actually ben credited with the such infamous feats as the asination Archduke Franz Ferdinand of Austria, thus beginning WWII.
-Hey, who do you think would win in a fight between Luigi and Vin Diesel?
-I don't know thats too tough to answer, but the one thing we do know is that they could both kick the shit out of that pussy Mario.