Mario wins a Manison for a random Contest and invite Team Sonic to to go with him to check out this Manison. Expect one certain duck accidently forgets and fells asleep and forgots that he was supposed to go along, until his nap was interuptted by Luigi who is worried that his brother or the other members of Team Sonic.
So the two of them go to the manison that Luigi won, and try to find the where abouts of their friends. While at the spooky mansion, Daffy and Luigi meet Professor E. Gadd who gives the Poltergoist 3000 and the EctoSucker 2500 , and that he had several ghosts captured and turned into portraits, but they were released by King Boo.
Luigi and Daffy enters the mansion, sucking up ghosts and finding keys, while meeting Toad and Happy The Cat along the way, until he encounters a portrait ghost, Neville. He defeats him, sucking him into the Poltergust. He does the same to Lydia, Neville's wife, and fights their baby, Chauncey, who sucks Luigi into his crib and fights him as a giant ghost, but is defeated and sucked into the Poltergust, which begins to get full, so Luigi returns to E. Gadd's lab and empties the Poltergust, turning Neville, Lydia, and Chauncey back into portraits. What becomes of the common ghosts is unknown.
Luigi enters another area through a previously blocked door and fights more ghosts. After defeating the Floating Whirlindas, he enters the Storage Room and hits a switch, which opens a trapdoor where 50 Boos and their leader, King Boo, are hiding. All of them escape, flying into different rooms of the mansion. Luigi returns to E. Gadd's lab and E. Gadd tells him that the Boos were the ones who released the portrait ghosts, and Luigi must capture the Boos to weaken their power, as they are stronger in greater numbers. So Luigi goes through the many rooms of the mansion, vacuuming up any Boos he sees. He also meets Madame Clairvoya, a fortune teller ghost, who tells him to bring her any of Mario's items he finds lying around in the mansion so she can get details on his whereabouts. The items are: Mario's hat, Mario's glove, Mario's shoe, Mario's letter and Mario's star. After sucking up Shivers the butler, Melody Pianissima, Mr. Luggs, and Spooky the dog, Luigi enters the Cemetery and fights the shadowy ghost, Bogmire. He defeats him and sucks him into the Poltergust, which he then empties at E. Gadd's lab to turn all the Portrait Ghosts into portraits.
Luigi enters a third area into the courtyard. Down the well, he sees into King Boo's altar, and discovers that King Boo has Mario imprisoned in a portrait. He goes through new rooms of the mansion, finding Mario's items and vacuuming up ghosts, including portrait ghosts Biff Atlas, Miss Petunia, Nana, Slim Bankshot, and twins Henry and Orville. After Luigi brings Madame Clairvoya enough of Mario's items, she tells him that she sees Bowser in a vision, which is shocking because Mario defeated Bowser, and she suspects that King Boo revived him. With her job done, she tells Luigi to suck her into the Poltergust so she can return peacefully to her portrait. After he does so, and defeats enough Boos, he enters the balcony and fights Boolossus, a big Boo made up of 15 Boos. He throws him into a spiky statue to split him into the 15 Boos and sucks them all into the Poltergust. He then empties the Poltergust at E. Gadd's lab to turn all the portrait ghosts, including Boolossus, into portraits.
When Luigi enters Area 4 in the attic, the mansion is suddenly struck by lightning and it goes dark. He then goes to the breaker room to turn the power back on, but finds it locked. Luigi looks for the key and soon encounters a ghost named Uncle Grimmly and defeats him to get the key. After he turns the power back on, he catches more Boos and portrait ghosts, including the Clockwork Soldiers, Sue Pea, Jarvis, and Sir Weston, before entering the room of Vincent Van Gore, one of the most prominent portrait ghosts who is painting regular ghosts. He sends several waves of ghosts after Luigi, but Luigi defeats them all, causing Van Gore to go into a state of depression, and Luigi sucks him into the Poltergust without much resistance. He then goes to the Secret Altar down a creepy hallway in the basement and encounters King Boo, who reveals that he was the one who told Luigi that he won the mansion in a contest, and set it up as revenge for all the trouble they caused him (though they may not have met him before, they have been fighting against Boos for years, plus King Boo works for Bowser). King Boo goes into Mario's portrait (which turns into a Bowser portrait) and sucks Luigi into it. In an arena resembling the roof of the mansion (and with a slight resemblance to the arena at the end of Super Mario 64), Luigi fights Bowser (as Madame Clairvoya had seen), but when he hits him in the head with a bomb, it is revealed to be King Boo piloting a giant Bowser mecha. Luigi defeats King Boo and sucks him into the Poltergust.
Luigi returns to the lab and turns all the portrait ghosts, including King Boo, into portraits again. E. Gadd reverses the Portrificationizer to release Mario, Sonic and Naruto from his portrait. After Mario, Sonic and Naruto goes through getting electrocuted, squished, being swirled around in a shell structure full of water, etc (The part where it slows down is when Mario returns to 3D)... He enters through some tubes and ends saying: "Oof!". Then Luigi walks up to the part where he puts his Poltergust 3000 in and says: "Mario?". Then Mario flies out of the tubes falling on his head. Luigi ends up falling but sitting. When Mario gets into a sitting position, Luigi gets a well deserved laugh, after seeing a frame around his brother's neck. Since King Boo has been defeated, his illusion of a mansion fades away, though the money and jewels Luigi and Daffy collected in the mansion was real, and with it he gets a new mansion or house.
- Things that are different from the original Game (Yes, it's a parody of Luigi's Mansion)
- Instead of a Gameboy Horror, they use a Horror DS Spook (Nintendo Ds Lite)
- Guest Starring: Drake, Lauren, Zoroark, Zorua, Dipper and Mabel Pines, Janet (Wendy in Gravity Falls) and Molly Harper the Hedgehog, Walter Wolf (Minor Cameo), Janet's Friends: Tambry, Robbie, Lee, Thompson and Nate
- Debut of the latest new members for Team Sonic: Slappy and Skippy Squirrel from "Animaninacs" (They're Dracoknight's favorite characters from Animaniacs and can acutally write with them in the stories)
- Each area or section of the Mansion, has one of the Memebers of Team Sonic and Janet's Friends stuck in a portraits expect for Happy the Cat, Molly Harper the Hedgehog, Dipper and Mabel and Janet
- Area 1: Oswald, Tails and Sakura
- Area 2: Conan, Dororo, Koyuki and Amaterasu
- Area 3: Shadow, Sasuke, Wendy M., Lucy and Knuckles
- Area 4: Erza, Aqua, Carla, and Conan
- Final Area: Mario, Sonic, Naruto and Natsu