Roy's Rowdy Rooftop
From the Super Mario Wiki, the Mario encyclopedia
This level features a boss battle with Roy. Roy's sole tactic is walking around, including along walls and ceilings, reopening any doors that have been closed by passing by it. Mario must jump on Roy to briefly stun him; he can jump on Roy again to stun him for a longer period of time. The level consists of five floors, with anywhere between two to six doors on each floor.