This level revolves around rotating floor mechanics, and also introduces the Octoomba enemy. These enemies resemble octopi and will spit out cannonballs at you, shooting three in a row. Unfortunately, they are resistant to pretty much all attacks, with the only way to defeat them being Ground Pounds. The stage is pretty linear at the start, so continue along, ignoring the one platform with a bunch of coins, until you reach a long red bridge with a number of Octoombas on it. As you cross this, you can hop to the lone blue platforms, but you want to make a pit stop at the one on the right.
There will be a brick above you, but don’t break it, as Green Star #1 is hanging above it. Of course, a nearby Octoomba might also break the brick with one of its cannonballs. Continue along to another long bridge of rotating platforms, although there will be some Dash Panels on the one side, which makes it easier to cross without being tossed off of it. The next part has you jumping over some gaps while not falling off, leading to a Warp Box and bringing you to the Checkpoint Flag. Jump up the next set of platforms to find three Octoombas relatively close together.
You will probably notice some invisible ?-Blocks near them (the explosions from the enemies’ attacks will likely reveal the blocks), which will allow you to reach the top portion here. There will be a tall wall of rotating platforms up here, but they will rest vertically. Of course, there is the Stamp at the top, but it’s a bit tricky getting it. It might be possible to grab the Stamp without the Cat Suit, but it makes it so much easier. Continue the level and when you get to the large set of rotating platforms, you will find Green Star #2 on a red one on the left side.
Once you move on, you will find two tiers of platforms, with the top one leading to a Warp Box. You should see what’s coming here, so stick to the lower path and at the end, you will find Green Star #3. Return to the beginning portion and take the top path this time, using the Warp Box to arrive at the Goal Pole area. Take note of the special guest here, as you jump up to the top of the flagpole.