Successfully complete World 6 to unlock World S.
Collect all 120 gold stars and 120 green stars to unlock the Grandmaster Galaxy in World S. This is a 2D level with a Comet Medal and one star to collect.
Collect "The Flotacious Blimp Fruit" star in the Tall Trunk Galaxy to be able to talk to Luigi at the beginning of certain levels and control him.
Defeat Bowser at Bowser's Galaxy Generator. Then, check the Mail Toad, and there will be a message from him. Enter the "L" on the spaceship to switch to Luigi, and play as him on any level.
Successfully complete a level with Luigi to unlock a ghost of the developers completing that level, which you can try to beat.
Collect 9,999 coins to unlock all the Luigi ghosts without having to complete each level with Luigi.
Successfully complete the game with 120 gold stars to be able to collect 120 green stars.
Deposit the indicated amount of Star Bits with Bank Toad to unlock the corresponding bonus:
- Glasses: 1,000 Star Bits
- Spear and shield: 2,000 Star Bits
- Pickaxe: 4,000 Star Bits
- Diver Toad: 6,000 Star Bits
- Explorer Toad: 8,000 Star Bits
- The Perfect Run (Grandmaster Galaxy Daredevil Run): 9,999 Star Bits
- Spear and shield: 2,000 Star Bits
Collect 9,999 Star Bits for watermelons to appear instead of coconuts.
Collect 120 stars to mark that saved game profile with a silver crown. Collect 240 stars to mark that saved game profile with a gold crown. Collect 242 stars and become the "Master Of Galaxies" to mark that saved game profile with a platinum and jewel crown. Collect all 120 Power Stars and defeat Bowser again to mark that saved game profile with a Rosalina icon.
Collect the final star (The Perfect Run) in the Grandmaster Galaxy to have your death count appear on your saved game file.
In Supermassive Galaxy after the mid-way point of the "Huge Trouble With Big Wigglers" level, there are three giant Koopa Troopas in a cylindrical area. Once you reach the area, run to the right and perform a Long Jump to land over the giant Koopas shell. Gradually keep moving right (you can release A) to keep jumping on top of the Koopas shell and getting extra lives. You can get 99 lives in approximately two minutes. Note: Your 99 lives will not be saved once you turn off the game. This trick must be repeated to get the lives back.
Another way to get infinite lives in the "Huge Trouble With Big Wigglers" level in Supermassive Galaxy is by going to the 1UP Mushroom floating above the gap between the "Tip Network TV" block and the next block. Long Jump over this gap to collect the 1UP, and then Long Jump back and speak to the TV. The TV will show you how to perform the Long Jump through a short "Tip Network" video. Once the video is finished, the 1UP mushroom will appear again. Collect the 1UP, and talk to the TV, it the 1UP will appear again. Repeat this as many times as desired.
Hold A to jump, and before finishing the fluttering (while still holding A), press Z to crouch mid-air. Quickly release A, then press A again, and repeat. This may require some practice. This move will allow you to slowly go anywhere.
Jump, shake the Wii-mote to spin, then quickly press Z to perform the Super Ground Pound.
Get a running start, then do a triple jump. As soon as you land, do a long jump to get twice as far. Note: This is easier to do if there are no gaps to avoid.
Go to a location that is high above deep water (for example, the Starshine Beach Galaxy). Run up the small sandy incline at the beginning. Look for a wooden plank hanging off a side. Have Mario move to the edge, and he will look down at the water. Turn around while standing there, then hold Nunchuk Z and press Jump to perform a flipping back flip dive.
While on ice, press Z to skate backwards.
Press Z to crouch to avoid their boomerangs. Walk over to the Boomerang Bros. while crouched, then spin to kill them.
If you see Luigi at the beginning of a galaxy, have player two point him and press A. Then, have player two spin to make Luigi give out Star Bits.
Press Up, Down, Left, or Right on controller two to make sound effects on player one's Wii-mote. Press Minus, Plus, 1, and 2 on controller one to make sound effects on player two's Wii-mote.
During the credits, collect a Bee Mushroom, and wait for the Shiverburn area to start. When the page flips, fly toward the screen before you appear. If done correctly, you should die by falling. The screen will turn black while the sound effects from the credits play. At the end, it will read "THE END" with "TOO BAD" in the background.
The Twisty Trials Galaxy resembles the secret level of Ricco Harbor in Super Mario Sunshine.