Super Mario 3D World: Bowser-B -- Hisstocrat Returns

To the right of the stairs in an invisible block with a Super Bell. Take the gondola to the arena. Hisstocrat is a different color and the fireballs that rain down remain in pools for a while. Climb up the snakes and stomp Hisstocrat's head three times to make coins and the Green Star appear. The pipe leads to the flag. You need to complete Bowser-A to continue.