Baby Luigi
Baby Luigi is a character in Nintendo's Mario series, similar to Baby Mario. He is the infant version of Luigi, although he has appeared in Mario Kart: Double Dash!! alongside his older self. It is generally accepted that these games do not have storylines and merely offer extra playable characters for greater variety. Baby Luigi first appeared in Super Mario World 2: Yoshi's Island where he got kidnapped by Kamek, only to be rescued by his brother Mario and Yoshi later on. Like his older self, Baby Luigi is voiced by Charles Martinet.
Baby Luigi more recently appeared in Yoshi Touch & Go, where Yoshi must rescue Luigi by throwing eggs in order to hit the Toadies carrying him. In the multiplayer mode, the second player's Yoshi will be carrying Baby Luigi instead of Baby Mario.
Baby Luigi rides along with Baby Mario in Mario Kart: Double Dash!! in a converted baby carriage and appears in Mario Superstar Baseball as unlockable character with speed ability.
Baby Luigi also stars in Mario & Luigi: Partners in Time, along with Baby Mario, his older self, and Mario. His abilities in battle appear to be identical to those of Baby Mario. The game explains the co-existence of the two sets of brothers in this game by saying that Mario and Luigi are sent back in time after an experiment with Princess Peach goes terribly wrong. They must battle the evil Princess Shroob to restore order to the shattered past of the Mushroom Kingdom.
Luigi's voice
Unlike Mario, whose voice has remained basically the same since its debut in Super Mario 64, Luigi's voice has fluctuated between high and low-pitched varieties throughout games. When his voice was first introduced in Mario Kart 64, its was considerably lower in pitch than Mario's, however, in Mario Party, he possessed a much higher pitched voice which was similar to Mario's. He retained this higher voice in Mario Party 2 and also had a high voice in Super Smash Bros. In Mario Golf, Mario Tennis, and Mario Party 3, however, his voice returned to a lower state. Since then, with the exceptions of Mario Kart: Super Circuit and Super Smash Bros. Melee, games have consistantly given Luigi a low-pitched voice.
Luigi's age in relation to Mario's age
Luigi is now generally accepted as the younger (yet taller) brother of Mario, though in the game Super Mario World 2: Yoshi's Island, he was said to be his twin brother. This was possibly either a mistake, or a fact that was later changed, as the remake of that game (Yoshi's Island: Super Mario Advance 3) does not refer to Mario and Luigi as twins, but rather as brothers.
Luigi outside of the games
Though Luigi has become less prominent in the games lately, he would accompany Mario in all of his jumps to other forms of media, with the exception of the Saturday Supercade.
His film debut came in the obscure 1986 Mario anime movie, The Great Mission to Rescue Princess Peach, where he was voiced by Mizushima Yu. He does not appear in the three Super Mario Bros. 3 OVA films until the end of the Shirayukihime story, where he saved the day. Afterwards, he was a regular on The Super Mario Bros. Super Show, which cast Danny Wells as both his live portrayal and voice actor. Like his brother, Luigi's voice actor changed in later cartoons, in his case to Tony Rosato. Notably, on The Adventures of Super Mario Bros. 3, Luigi starred in "Life's Ruff", the only Mario cartoon episode where Mario did not appear.
When Mario made the jump to comics in 1990, Luigi made the jump with him. Oddly enough, in the Nintendo Comics System, Luigi did not play the role of Mario's sidekick as frequently as in the cartoons, to the point that in one story Mario referred to Toad as his sidekick.
Luigi played quite a different role in the Super Mario Bros. movie, where he was portrayed by John Leguizamo. There, Luigi was a more easy-going character in contrast to the cynical Mario of the film.
Luigi also regularly appears in the unofficial web comic series Neglected Mario Characters. In the earlier comics, he was portrayed as fed up with having to play second fiddle to Mario all the time and often defected to the Koopas. When he did this, he assumed his alter ego Darth Butch. In this form, he has mastered the power of the Worse and represented the "Slightly-Black Side." In modern comics, he is portrayed as the "unsung hero," often has weird dreams, and is very gullible. He is also quite taken with Celes and Daisy. He was one of the Mario Busters along with Toad, Stanley the Bugman, Dr. Donez, and Lemmy the Lemming. He is also one of the few characters to appear in multiple Deathmatches and remain undefeated. Another running gag with Luigi is to not put him in comics and then have him complain about it at the end.
As with that strip, Luigi is usually portrayed in fan-made Internet material as being bitter towards his brother, such as in "The Colour of Envy", where he enlists Wario to help him conquer the Mushroom Kingdom and imprison Mario. Ultimately, Mario becomes Fire Mario, KOs Wario and rescues Toad, who has been severely wounded.
The most notable exception, however, is Randy Solem's Rise of the Mushroom Kingdom Flash series on the Video Game Director's Cut website. In this series, Luigi is shown avenging Mario's death in an extended dream sequence in which he storms Bowser's castle with a bloodthirsty army of Yoshis and Toads. Upon finding out that it is in fact Wart who is responsible for Mario's murder, Luigi wakes up just in time to find out that Wart's now committing the deed for real. Luigi manages to save Mario, but in the process dies himself. While Mario storms through Subcon in a quest for vengeance, Princess Peach ventures to find a 1-Up Mushroom with which she uses to restore life to Luigi, who then flies to Subcon himself to help Mario defeat Wart.
