Dr. Potter

Dr. Potter is the seventh boss encountered in Luigi's Mansion 3. He is encountered and fought on the seventh floor after Luigi locates him at the greenhouse. Defeating Dr. Potter rewards Luigi with the elevator button to the eighth floor.

Appearance
Dr. Potter is a green ghost with long, bushy white beard and eyebrows and a yellow hat with a white flower sticking out. He wears a dark brown coat and backpack.

Luigi finds the eighth floor button seemingly unguarded, although before he can fully celebrate, he finds a watering can that causes a sapling to grow into a Venus flytrap, with Luigi accidentally feeding the button to the flytrap out of shock. Dr. Potter then reveals himself and taunts Luigi before watering more nutrients to the flytrap, causing it to become gargantuan in size. He then flees, although not before laughing one last time at Luigi.

After Luigi gets the button out of the Venus flytrap (and is forced to backtrack back down to stable ground after dropping it to the ground), Dr. Potter then intercepts the button with a Venus flytrap of his own and then confronts Luigi, although Dr. Potter unintentionally has his flytrap expose a buzzsaw.

Battle
Dr. Potter mainly relies on his Venus flytrap to attack. The Venus flytrap attacks in three different ways: a forward lunge, a swipe, and a downward lunge.

To beat Dr. Potter, Luigi must trick the Venus flytrap into doing a forward lunge on a plant bud (the other two aforementioned moves destroy the bud instead), then use a buzzsaw found on the field to sever the Venus flytrap's neck, leaving Dr. Potter vulnerable to being sucked in. After being attacked the first time, the Venus flytrap will begin swiping and lunging downwards more frequently. After being defeated, Dr. Potter will struggle to escape, only for his beard to get caught in the Poltergust G-00, followed by the rest of his body. He will then reach out of the nozzle of the Poltergust G-00, swing his arm around for a few seconds, and then throw the elevator button onto a leaf high above the battlefield, out of Luigi's reach. A few seconds later, Dr. Potter's watering can will pop out of the Poltergust G-00, which is vital to obtain the elevator button to progress to the next floor.

Trivia

 * The flytrap Dr. Potter uses during the battle is very similar to the one in Luigi's Mansion: Dark Moon.