Luigi

From The DS Ultimate Wiki

Luigi is Mario's brother, and an important character in the Mario series, first appearing in the original Mario Bros. He for years was often player 2's character in said series, and from a mere palette swap of Mario, Luigi has more recently become his own character, with an interesting personality.

There is some confusion as to if Luigi is Mario's twin, or his younger brother. In Super Paper Mario Luigi refers to Mario as his "big bro." In the Super Mario Super Show!, Luigi states he is the bigger one, even though he is younger. Yet in Yoshi's Island, Luigi and Mario are brought to their parents by the stork together, hinting they are twins. The Brawl description of Luigi states he is "Mario's younger twin brother", which is probably just a mistake upon translating the game.

Luigi ranges from almost every Mario sports game to fighting his way through the Smash bros. series. His first game based on him was "Mario is Missing" for the SNES. Although this was an educational game it did launch Luigi's Breaking free from Mario and becoming his own character. Although Luigi did not appear in Super Mario 64 he did appear in Mario Kart 64 and Super Smash Bros. Then on the Gamecube, Luigi played starring role in his second game Luigis mansion. This game presented the personality we see in Luigi today.