Super Mario Galaxy 2/Battle Belt Galaxy

Star 1: Mini-Planet Mega-Run
In this mission, you will need to defeat every enemy in each area to advance. You start on a planet with a single Mini Goomba; defeat it and take the Sling Star that appears. The next planet has Li'l Cinders. Defeat them and move on, but don't forget the Comet Medal. The next planet has urchins, and you'll need a fire flower to defeat them. Conveniently, one is right on the other side of the planet. Grab it and torch all the urchins. Before launching to the next planet, wait for the fire flower to respawn and get it. That makes defeating the Crabbers on the next planet much easier. Otherwise, you'll have to stop them with a spin or stomp, then spin their backside. After that is a pink Starshroom with a checkpoint, coins, and a Sling Star.

Next is a planet with Jack-O-Goombas. The best way to defeat them is to ground pound. Defeating them gives you a key that opens the cage, giving you access to the pipe. Take said pipe to an underwater area with Boos. Get the shell at the bottom, then hold to slow down. Then, shine the light around to get all the Boos. Take the Sling Star to go back out the pipe, then take the Sling Star that appears on the planet to another Starshroom. This time, there is a Luma Shop. If you are doing the hidden star, it's a good idea to get a Life Mushroom. Otherwise, get a 1-Up or ignore it. Hit the checkpoint and move on.

You'll land on an ice planet with Li'l Brrs. There is a Hungry Luma here, but ignore it unless you're going for the hidden star. Note that spinning will make you skate, so if you don't want to skate, then jump and spin in midair to stun the Brrs. Once you get them all, sling to the next planet. This one has Undergrunts. Wait near the path until one comes, then ground-pound to stun it. Then, spin to defeat it. Do the same for the other one. Get another key which opens the cage, then take the pipe. This will take you to a 2-D donut-shaped gravity section. The gravity will switch between pointing in and out. There are Swaphoppers here, but you can only jump on their yellow undersides, so watch the direction of the gravity and plan accordingly. Take the pipe back out.

The next and final planet has Silver Chomps. The only way to defeat them is by using the springy green plants; you'll have to spin them into the Chomps. They will also try to roll towards you, so be careful. Defeating them all will give you a key, which grants you access to the Power Star.

Star 2 (Prankster Comet): Mini-Planet Daredevil Run
Repeat Star 1 with only 1 HP.

Star 3 (hidden): Snacktime for Gobblegut
Enter Star 1 and feed 20 coins to the Hungry Luma. Take the newly formed Launch Star to a new planet, and Fiery Gobblegut will show up. The strategy to beat this boss is the same as normal Gobblegut, but with a few differences. His body is on fire, so you can't touch him. Also, whenever he eats part of the ground, he will leave behind a lava pool that you need to avoid. Hitting the last three bulges during the first phase will make this fight much easier, as they will become harder to hit in the second phase when he gets faster. There are many coins around the planet if you need them for health.