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.
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, though it regrows), 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 him. 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, just before the plumber finishes vacuuming him up. 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.