Super Mario Galaxy 2/Stone Cyclone Galaxy

Star 1: Silver Stars on the Cyclone
This entire galaxy takes place on a single planet resembling the Cyclone Stone in Beach Bowl Galaxy from the previous game. However, the Thwomps and Tox Boxes here move much faster, and there are now Octoombas patrolling the planet as well. Like Thwomps, Tox Boxes can instantly kill you if you get crushed, but one side of them is hollow, so standing at the right spot as they roll over you can prevent you from getting squashed. There are also some Time Switches to slow down time and make the Thwomps and Tox Boxes more manageable.

The first Silver Star is located just down the path, on a raised part of the road with an Octoomba. You will then have to time a long jump to clear a quickly pounding Thwomp. Further down the path is a Tox Box, with a Silver Star located right in its path. There is also a Time Switch nearby. Pound it down to slow down time, which will make it much easier to collect the second Silver Star without getting crushed. Further on, you must jump on to the cylinder of rapidly moving platforms, one of them that contains the Comet Medal. There is also a Time Switch on one of the stationary platforms to help you get to the other side.

After the rotating cylinders is a single loop with a Tox Box rotating around it. There is another 1-Up along the loop, as well as the third Silver Star. Use long jumps when going along the loop, as you can't outrun the Tox Box, and quickly find a safe spot to stand whenever it gets too close. Somewhere along the loop is a path that takes you up to another Tox Box. Stand on the second platform along the Tox Box's path from the left as a safe spot. As the Tox Box approaches from above and as soon as it covers you, start running toward the time switch.

The switch should make the next Tox Box easier to bypass, and there is also a 1-Up on a vanishing platform to the left of the Tox Box's safe spot. From there, run right to the tile with the question mark block. Wait until a Tox Box from the right reaches the spot beside you, then dash after it until you reach its safe spot, which is a bare tile instead of the cobblestone tiles around it. Once the Tox Box has turned back and stated moving the other way, continue to the right and down the path to find the fourth Silver Star. The final Silver Star is not far away, but there are two fast moving platforms between the star and you, which can push you off if you're careless. Clear the two platforms with a combination of a long jump and a spin jump and collect the final Silver Star. The gold star that spawns is located near the location of the fifth Silver Star. Just walk up to it and grab it to end this difficult level.

Star 2 (Prankster Comet): Tox Box Speed Run
For this mission, you have to make it to the star at the other end of the planet. You start with a minimal time, and as usual, must collect timers to increase your time. There are no Time Switches and the enemies are still as fast, but the absence of Silver Stars means you can skip certain sections of the planet. The timers are mostly located on where the Silver Stars and Time Switches were, but some of them can be skipped. For instance, you can long jump from where the Silver Star was located right on to the section with the moving platforms, skipping a Thwomp and a Tox Box and letting you reach the remaining timers quicker.