999.
In Super Mario Galaxy 1 you can get 121 power stars, but in Super Mario Galaxy 2 the star gauge can hold 240 stars.
5
as many as it can
There is currently no Super Mario Galaxy 3. If you mean Super Mario Galaxy 2 there are 242 stars.
There's 150 power stars in Super Mario 64 DS.
in Mario 64, you can only get about 280 stars. But if you have the r4 game card with the cheats, you can get 280 stars and find more.
6 stars
122 power stars and 120 green stars.
120 (242 if you count the Green Stars)
any number of stars with luigi or all 150 stars
Although there are 150 stars in total, you only need 80 stars (and Mario) to complete the game as this is the number of stars you need to get into the final Bowser level.
Rosalina is not in Super Mario Kart. She is in Mario Kart Wii.