Robo-Luigi

Robo-Luigi is a boss that can be found in Fifth Floor B of Princess Peach's Castle. They have the same moveset as Luigi, as well as having a Flaming Hot Smoke attack, and is floaty. If you defeat Robo-Luigi, you can unlock the sixth mission of Robo Station Way, a buffed version of Robo-Mario. Beating Robo-Luigi unlocks them as a playable character. When defeated, the player unlocks Ultra Hard Mode Plus X.