Grandmaster Galaxy unlocks after collecting the first 240 genuine stars: 120 regular stars and all 120 Green Stars. Bronze Stars from the Cosmic Guide do not replace the required Power Stars. The two missions here raise the final total to 242.
The Ultimate Test — Yoshi and the flowers
Begin with Yoshi and use the grapple flowers to cross the opening gaps. Face the next flower before releasing the current one. Keep away from Paragoombas and mines; a rushed tongue grab can aim at an enemy instead of the flower you need.
Flipswitch Panels
Step on every blue panel to turn it yellow. Plan a continuous route across the grid and use the stable surfaces to change direction. Avoid the beams while checking any panel you missed. The Launch Star appears once the full set is active.
Cloud Mario and the electric maze
Take the Cloud Flower and leave Yoshi behind. Use the wind to carry a created cloud through the maze, watching the electric boundaries. Build a new cloud near the top of a jump when you need height. Keep the next Cloud Flower in view so you can refill the three-cloud supply before committing to another long crossing.
The rotating platforms
A spin both creates a cloud and changes the platform arrangement. Before spinning, identify which surface will support your landing afterwards. Spend a cloud only when it creates a needed foothold; unnecessary spins can remove the platform you were heading towards. Refill at the next Cloud Flower before proceeding.
Pull Stars
Use short pulls to carry Mario through the electric obstacles. Release a Pull Star before it drags you into a barrier, then catch the next one from the safe side. Let Mario settle when you need a precise change of direction, and keep clear of the mines around the route.
Hammer Bros., the Comet Medal and the ending
On the last combat platforms, avoid or defeat the Hammer Bros. as you move towards the three Boomerang Bros. at the end. The Comet Medal is out on the far-right side near the small platforms and torches; collect it during this first mission. Defeat all three final Boomerang Bros. to reveal the Power Star. Clearing the earlier Hammer Bros. is optional, but removing one can make the next jump safer.
Unlock The Perfect Run
Finish The Ultimate Test and collect its Comet Medal. On the Wii version, store 9,999 Star Bits with the Banktoad to make the final Prankster Comet appear. Check the banked total, rather than assuming carried Star Bits satisfy this requirement. The medal here is the forty-ninth and last medal when all other galaxies have been cleared.
The Perfect Run
Repeat the entire course with one health point and no Checkpoint Flags. Extra Choppahs and Space Mines make the opening less forgiving. Practise each section in The Ultimate Test first, then use the same deliberate platform and Cloud Flower timings in the final attempt. A hit or fall restarts the run. After defeating the three Boomerang Bros., take the new Launch Star to Rosalina and collect the last Power Star for 242.
