Ride the gondola down to a rooftop that is being bombarded with fireballs, which will never end, but it is restricted to this roof. Keep moving to avoid being trapped, bypassing the Fire Bros, until you reach the highest portion in this first area. Drop off the roof here, to a smaller one, where you will find Green Star #1. Jump back up and take the clear pipe, launching yourself to the next set of roofs. One of the bricks will contain a power-up (Super Bell), so grab it and go up the incline, to a set of rotating platforms. There will be a Bully on each of the platforms.
At the top of the wheel portion, there is a ?-Block that contains a power-up. Your goal on the rotating platforms is to knock all of the Bullies off, and upon doing so, you will unlock Green Star #2. Continue on to the right, taking the gondola into the next area. Approach the tower across the bridge to start the final battle.
BOSS - Meowser
Bowser equips a Super Bell and transforms, now with the ability to climb walls like you do. Work your way up the scrolling tower, waiting for Bowser to pop out and climb around, before progressing through the pipe and into the clouds. On the third layer, you’ll find the Green Star Ring, so time it that the Cloud Platform moves towards you when you hit so you can make a beeline across, then up for Green Star #3. Wait for Meowser to climb by you, then take the pipe to the top level. Rush up past the fireballs Meowser fires and hit the Red POW Block to temporarily defeat him.
Grab the clock pickup before entering the Clear Pipe, then tag the Checkpoint Flag. This next part can be challenging, as you will be facing multiple Meowsers now, thanks to the Double Cherry power-up he seems to have used. Propel up using the Jump Panel and avoid cracks in the wall, as Meowser will be busting through those walls. There are trapezes to aid in climbing up, but with the Cat Suit it’s simple enough to climb from cloud to cloud. As you reach the top, rush around the steps to find multiple Meowsers tossing fireballs but also a Super POW Block. Hit this thing four times to send Meowser flying away.
Take the clear pipe to the Goal Pole area then climb the tree for the Stamp before finally freeing all the Sprixie Princess’ and saving Sprixie Kingdom.