Big Boo Battle

Big Boo Battle is a level in Super Mario 64 DS accessed via a painting in Big Boo's Haunt, rewarding the player with Luigi upon completing the level. It's boss is King Boo, who is erroneously referred to as a Big Boo in the level's name and in dialogue.

Geography
Big Boo Battle begins in a maze with several pathways, with the wrong path leading the player to the beginning of the level. Several Boos are scattered around the level, alongside some Power Flowers. Eventually, there is a room with a black brick, a bridge, and a painting only accessible using the Vanish Cap ability, and the teleport to the boss battle with King Boo, which is a large mirror room similar to the one seen in the Second Floor of Princess Peach's Castle.

Stars
There are 2 stars in this level. The first one is obtained by collecting 8 red coins, requiring Mario to use his balloon Power Flower ability to obtain some red coins, and the second star is obtained by using Luigi's Vanish Cap ability to go through a painting at the end of the level and reach the star in the level.

Super Mario 64 Manifestation
In some personalized copies of Super Mario 64, Big Boo Battle can supposedly appear as a special level that usually appears the same, with the appropriate changes in order to fit the game, such as making the Power Flowers into the power-ups required for the area unless the Power Flowers manifest in the copy alongside the level. King Boo can also appear in this manifestation, though can be replaced by a Big Boo.

Name Error
Despite this level's boss being King Boo, the name refers to them as Big Boo. The dialogue in this level, specifically the boss fight, also have this error, despite the fact Big Boos are also present in the game and King Boo being a different boss from a Big Boo.