Breaking into Bowser's Castle
Run up the slope and avoid the fireballs. Hop on top of the floating wooden box and from there on the next platform. Run up the slope again here and do not be surprised by Magikoopa. This is followed by a 2D section.
Touch the Checkpoint Flag and jump backwards on the brown block to reach the Comet Medal. Then continue along the path and take care of the leaping lava. Finally, you swim back outside to the next Checkpoint Flag.
Let the stone block come towards you, dodge it and make a ground pound on its back. You don’t necessarily have to defeat the next stone block, you can just walk around it. Then walk down the railing and follow the path. At the very bottom you jump to the lower platform with the circulating fireballs. Run around them clockwise and always jump as soon as you get into distress. Then the same follows again, where you can reach a Launch Star below.
Again touch the Checkpoint Flag and smash the three Bowser stones by running a ground pound on the ball in the respective direction. So you get directly to the final fight against Bowser.
Boss Fight: Bowser
The battle is the same as with “Hot!” Bowser’s latest toy from World 2. What is new is the shock waves caused by Bowser's Faust and the meteorites. You can just jump over them.
Gravity Star Speed Run
Select this challenge when the Prankster Comet appears.
With this comet star you have the task again to complete the entire level under time pressure. Again, the green watches are scattered everywhere, which you should collect as much as possible, otherwise it will be quite tight. Here, however, all were placed clearly visible, so that you will have no problems with it. With a little practice, this Power Star is done quickly.
Comet Medal
Just inside the castle, find the Brick Block near the checkpoint. Backflip onto it and jump into the medal overhead before following the changing-gravity route.
Green Stars — unlock requirement
Collect all 120 regular stars and defeat Bowser again to unlock the Green Star hunt. Choose the corresponding Green Star mission from this galaxy’s mission screen. Follow the detours below rather than collecting the normal mission’s ending star.
Green Star 1
Near the castle entrance, look for the sunken pillar in the lava. Backflip from safe ground onto the pillar and collect the star above it. Aim for the pillar top so you do not depend on taking lava damage.
Green Star 2
At the castle’s far end, stop beneath the ? Block. The star is above it. Use the block as your height reference and backflip followed by a spin into the target.
Check each numbered Green Star on the mission screen after collecting it. The routes finish immediately when the star is touched, including stars suspended over a gap.