You pretty much hacpve to fill the vases with fire from the fire Mario. First, you get the Mario. You go down to the gate and shake your wii remote to spew fire, thus opening the gate. Wait until the fire Mario wears out, get it again then rush through the gate to go to the two towers which look somewhat like this: |-| |-|with vases in front. You have to spew fire like before into both, if you succeed, a bridge opens. You climb through, until you reach the part where you have to get the star. Then, get fire Mario and run to where the platforms come out. Ride one, spew fire into the vases in front of the star. A bridge appears, you win the level.
Level 2
Rosalina will tell you.
It's a hidden star and can be found by simply going to any level
To get her as a file icon, you need to get 120 stars and clear the level in Bowser's Galaxy Generator. To get her on Starship Mario, you need to get all 240 stars.
By avoiding bullets and stomping enimies
Complete the first star from the Grandmaster Galaxy and have 9999 Star Bits stored in the bank.
7 times you must lose a life in the galaxy and then the super guide engages.
You must really stink, because that level is easy!
When you complete the bowser level after you get 50 stars and you have to complete the bowser level twice to get him
yes and no. there's a secret level in the space junk galaxy with a planet that looks like Yoshi in it, but the actual character doesn't make an appearance.
You meet him a lot on different galaxies, but when you beat the last level (i think) you can play as Luigi any time!
Try for the 122nd star, or just play on any level you want.