catch all the golden bunnys then you'll get the key, its a star :D
A star but you need to find 5 white bunnys, in order to get it.
To find "Wario key" Beat Chief Chilli, but first u have to get Luigi.
cheers yoshicart2010
You have to unlock Luigi and then use his invisibility power to go through the mirror, if thats what you are asking.
no but you CAN beat the first bowser battle and he will give you a key and not the basement is unlocked!
Go in the bushes, then you'll see a rabbit with a key. Just use your tongue and grab him, and he will give it to you.
To catch a rabbit, attack it (A) at the right second to nab it. If you are successful, it will give you a key to unlock a new mini-game.
If you mean that door in the rec room in Super Mario 64 DS with the number 8 on it, you just need to get 8 stars and then it will open. The course with Goomboss, who holds the key to the room where Mario is locked, is behind this door.
Beet bowza
yes
open a door with a lock in the area you obtaned the key in
dounnut plains 1
You do a favor for Merlee
fight the 2nd bowser
The keys unlock new areas. Example: The first time you beat Bowser you get your first key. Go in the doors like you're going to go to Big Boo's Haunt. If you turn into those other steps going into the basement, you open the door using the key. Figure out the next one.