Upon starting the stage, move forward and Long Jump over the gap to get to an arch. Cross the bridge there, being wary of the Bubbles that go across the bridge, as well as the Bully just beyond it. These Bullies can be quite annoying, as they are very aggressive and you have to continually knock them back with your own attacks until they fall in lava. Here, you will have two ways to go, but for now, head left and across the bridge that is retracting. Ignore the Mr. I if you want and continue onto the piece of platform that has its ends being dunked in lava.
Beyond that, there will be a sliding puzzle, featuring Bowser’s wonderful face. This is where the Red Coins will be found, but you won’t be needing them for this star, so it’s best to quickly move past the sliding puzzle before you accidentally fall in the lava. There will be another two Bullies past the puzzle, then a rotating platform with some Fire Bars circling around it. Quickly move past that and across the next sinking walkway, where a Big Bully will be waiting for you on a large platform.
The Big Bully is nothing other than an oversized version of the regular Bullies you’ve faced thus far. The jumping kick is one of the best ways to deal with the Bullies, as you can essentially press both the jump and attack buttons at the same time to perform one. The slightly problem is that if you accidentally press the attack button first, especially while running, Mario will perform a dive instead. Once you knock the Big Bully into the lava, the star will spawn on the nearby ledge. Use the steps, which will fall out from under Mario and not respawn, to reach the star.