Shadow Luigi

Shadow Luigi is the apparition of the ninth mansion and is the very mirror image of Luigi. It's attacks are the same as those of both Luigi and Shadow Mario. When defeated, Luigi receives the key to the tenth Mansion and receives the Shadow Cap which unlocks the Shadow Luigi Costume for Luigi.

Trivia

 * When Luigi faces Shadow Luigi, if he were to use the Advanced Gameboy Horror on him, Luigi would say "What the... is that... me? This is kind of odd. I'm fighting myself!"