Super Mario Galaxy 2/Chompworks Galaxy

Where the Chomps Are Made of Gold

 * First planet

You start out in an area with three Gearmos and a couple Octoombas. On a ledge above the area you'll also see a series of Chomps rolling by and crashing into a block at the end. The ramp leading up there is down only, so you'll need to take the platforms behind the pink Gearmo. Be quick, as the longer you stand on the platforms, the lower down they sink. When you get up to where the Chomps are rolling by, get in between them and head to the left where you can flip a switch to lower the block they're running into. Going the opposite way against the flow of Chomps by sidejumping will take you to a 1-Up Mushroom in front of where they're coming out. Back down on the lower platform, you'll need to stand on the blue square the Chomps run into so it's flush with the ground, letting a Chomp roll into the hole beyond it. When you get a Chomp in the hole, it will explode and reveal a Launch Star.

Here you'll have large Chomps rolling toward you and crashing into the Gearmo at the end. There is a blue platform on the left of the path the Chomps are rolling down, and two on the right. You need to jump from the platforms on the side onto the path behind the Chomps, then over to another platform before the next Chomp rolls into you. When you jump out to one of the platforms, spin in the air if you're going to land on one of the mini Chomps. There's also a green pipe on the second platform that will take you down to a room with three Lucky Cubes in it. The last platform has the Launch Star you can take to the next planet.
 * Second planet

On this planet, Chomps are rolling through the building behind you and you need to get one into the hole by where you land. There are some flip squares here that flip over when you spin and there is a 1-Up Mushroom at one end of the green seesaw. Head down to the left, jumping from platform to platform, and flip the switch on the other side to allow the Chomps to roll out of the nearby box. You will need to stand on the green seesaw and spin the red squares up so a Chomp can cross them and go up the green ramp you make. When the Chomp gets over the seesaw, you have to spin again to flip up the blue squares so it can cross to the hole and make the Launch Star.
 * Third planet

Grab the checkpoint here and make your way into the area with the hole and the Octoomba. In the distance you will see a Golden Chomp come rolling out of the lava and explode when it hits a raised platform. You need to stand on each platform along the rails as the Chomp comes to it to let it pass. Then, at the end of rails, you need to ground pound the blue button to raise the nearby blue platform when the Chomp is on it. This will allow the Chomp to roll all the way to the hole in the beginning, where it will explode and reveal the Power Star. If they're giving you trouble on your return route, you may want to spin all the Goombeetles off the path when you go over to the Golden Chomp.
 * Fourth planet

Stand on the far right of the first platform next to where the Chomp comes out of the lava and start running for the next one as soon as it rolls over it. This time stand on the blue end of the next platform that's closest to the camera, and when the Chomp passes, jump toward the camera to the green path there. From there, just run over and wait on top of the blue button for the Chomp to get there. When you see the Chomp just start to get on the blue platform, quickly jump and ground pound the button. Let the Chomp roll down into the hole, then go grab your Power Star.

Spring into the Chompworks
This time there are no platforms up to where the Chomps are rolling, but you can use the Spring Mushroom to spring up the ramp to the Launch Star. There is also a 1-Up Mushroom back where the Chomps are coming out if you are feeling adventurous. You can hop up the ramp with no problem, but you will need to spring to get up to the Launch Star, and you do that by holding when Mario lands and his springs start to bunch up.
 * First planet

Hit the checkpoint flag and spring up to the 1-Up Mushroom above if you want. There are no side platforms this time, so you'll have to jump over the Chomps as you head down to where they're coming out. At the other side, jump on top of the box the Chomps are coming out of, and you'll see another smaller ramp where smaller Chomps are rolling down. Jump over these ones too and jump into the Launch Star at the other side.
 * Second planet

Here is another checkpoint and a tall triangular wall platforms and spinning pegs in front of it. You'll need to use the Spring Mushroom to jump from platform to platform to reach the top where the Power Star is waiting. When you go up a couple platforms, you'll see a moving platform that goes up and down on your left. You can take this platform up or over to the ? Coin farther to the left. The ? Coin creates a tall line of coins you can jump through to earn a 1-Up. Above the moving platform you can get onto a large stationary one on the right, then either take the next platform up or hop down for the 1-Up Mushroom. When you take the platform up, you'll need to jump on a spinning peg, which leads to another spinning peg, and then the Power Star. If you fall from this part, keep holding so you land on the large platform in the middle and only have to go up one more platform.
 * Third planet

When you finish this level, a Spring Mushroom will appear on Starship Mario.

Cosmic Clones in the Chompworks (Prankster Comet)
You need to do the final part of the first star, where you guide the Golden Chomp, although this time trying to avoid the Cosmic Clones. Your approach to this will the same as last time, except you don't want to waste time spinning off the Goombeetles and you'll need to time when you get into place on the platforms so the clones don't run into you. When you first go over to the Chomp, stay to the left so your clones don't interfere with your path on the way back. A good technique to use is to walk a couple paces and stop, then walk a couple more and stop and continue doing this when you need to kill time while waiting for the Chomp.

Green Stars
In the first area with the Chomps rolling down toward the switch you need to flip, do sideflips over them by running away from them, then quickly turning back toward them and jumping. Eventually you will make your way to the back where the Chomps are coming out and can long jump out to the first Green Star. On the third planet, make your way to the end where you flip the switch to turn on the Chomps, but instead of flipping it, jump onto the box the Chomps come out of and then jump up to the roof of the building from there. Follow the rooftop back to the beginning of the planet and you'll find the second Green Star waiting.
 * Green Star 1 or 2

On the last planet where you have to spring up to the Power Star, get onto the metal conical roof on the right that looks like a screw and spring from the tip of it to Green Star 3.
 * Green Star 3