This post is about the upcoming Mario & Luigi: Dream Team!!!! The newest Mario Game!!!!!!!!!! For the 3DS!!!!!!
This game is a "Year of Luigi" game, meaning Luigi is super important in this game. Here is the plot that I know of.
Princess Peach, Mario, Star-low (from Mario & Luigi: Bowser's Inside Story), and Luigi go to Pi'low Island for a vacation. But when they get inside Pi'low Castle, Luigi sleeps on a magic pillow, opening a portal to his Dream World. And shortly after the portal opens, BOOM!!!!! Peach gets pulled in by a weird bat creature called Antasma. Then Mario jumps inside the Dream World after Peach. While in there, Mario meets Dream World Luigi. Exactly like normal Luigi, only he exists in Luigi's dreams. And by messing around with Luigi in the real world, it will alter the Dream World. Like for example, Star-Low can pull on Luigi's mustache, thus turning Dream World Luigi into a tree shaped slingshot. And when Luigi sneezes in the real world, a hurricane happens in the Dream World (It only affects enemies and blocks blocking the way). And Dream World Luigi can turn into hundreds of clones of Luigi called Luiginoids. Later down the road, Bowser shows up and learns that Antasma kidnapped Peach. Unfortunately, Bowser becomes enraged because apparently, only BOWSER is allowed to kidnap Princess Peach and NO ONE ELSE is allowed to do so. So he jumps down the portal and Mario and Dream World Luigi fight (and beat) him in a 2000-on-one fair fight. The Luiginoids filling 1999 of the good guys with Mario being the 2000th good guy.
This game is EPIC!!!! In fact it might be the most EPIC Mario game EVER!!!!!
Here is a gallery. NOTE: ALL IMAGES ARE FROM THE MARIO WIKI.
This is Mario and a few hundred Luiginoids (the Luiginoids are curled up in a ball).
Mario entering Luigi's Dream World.
For more info, please visit either Nintendo.com and/or the Mario Wiki.