How do you get Luigi in Super Mario 64 ds?

Answer 1

You need to have at least 16 stars and have gotten the ! boxes solid. Then you have to be Mario. Go through the door that has no number or star on it in the lobby and follow the boo into the garden. Then kill the big boo and go inside the Big Boo's Haunt level. Then, go around the rooms killing all the ghosts, until a sign comes up saying something like 'Here comes the big boo, the master of haunts'. Then enter the lobby (where a star has appeared on your map) and a huge ghost appears. Kill him and then go up the stairs that appear and collect the Power Star (or just triple jump up). This will force you out of the level as usual, but then go straight back to the garden, kill the big boo again, go into the box and go up the new stairs that have appeared. Enter the last door on the right. Then go onto the wooden platform and use the power flower to float to the level above it (or just wall jump up). Then beat the level (which is sort of like a maze). First, when you are on the merry-go-round type maze, make a right, then make a left, make a right again, then make another left, then keep straight and go down the hole. Once you fall down the hole, you will see a mirror. If you are stuck here, then walk slowly to the mirror. You will see a reflection of Luigi, then you will see King Boo on your right. Beat King Boo using the mirrors reflection, but the second time you go to attack him, he is visible without the mirror, then you get the Luigi key.
hold L + R AND PUSH A

Answer 2

Go onto the sun carpet in the lobby and go to first person perspective, and look to the light. fly to the castle-like thing and stomp down on the '!' red switch, this makes '!' boxes become usable! Luigi's key: Go to the Boo Garden ( courtyard with all the ghosts ) when you first enter, go to your left, there will be a BIG boo, when he is white, punch him, he will have a cage in him. jump on the cage and you will go in. in there is another world, after you complete a few levels -inside the house- stairs will come down. You MUST be MARIO at this point. You up the stairs and go to the door last on the right. there will be a little wooden edge thingy. now the '!' box should be red, jump under it, and WITH MARIO, get the flower, and will float up ( press 'B' ) and go to the door up top. hit 'R' to land go threw the door. there will be a Luigi painting on the wall, go threw it... now beat the Big Boo, and luigi is yours!