It has been confirmed that Luigi's Mansion: Dark Moon for the 3DS will feature four player local multiplayer. A scan from the latest issue of the Japanese magazine, Famitsu shows four Luigis, all dressed in different colours, sucking up a ghost with their Poltergust 5000s. There's also a screenshot showing all four Luigis exploring a room together.
This is certainly an interesting development; the first Luigi's Mansion was single player only, so a multiplayer mode in Dark Moon is very nice. The only question that remains is: will the entire game be playable co-op? Or will there only be specific things that you can do in multiplayer? Either way, Luigi's Mansion: Dark Moon is set for release some time in March this year, and we're definitely looking forward to it!
A couple of hours after this was posted, Nintendo of America posted a video to YouTube showing off the multiplayer mode of Luigi's Mansion: Dark Moon, called Hunter Mode. The mode looks like a co-op adventure to get rid of all the ghosts in the mansion by working together. They also confirmed that the multiplayer mode will be playable online as well as locally.