Cloud Flower

A Cloud Flower is a power-up from Super Mario Galaxy 2. It looks like a cloud with eyes and a stem. If Mario grabs one, he'll transform into Cloud Mario. As Cloud Mario, he'll be able to create clouds as temporary platforms by spinning. These clouds have faces on them. Additionally, he can only make 3 of them before needing to get another Cloud Flower. The Cloud Flower also improves Mario's jumping abilities, as he now falls slower and his long jumps are longer. However, if Cloud Mario touches water or takes damage, he will revert back to regular Mario, causing any of his cloud platforms to disappear. Cloud Flowers first appear in the Fluffy Bluff Galaxy. In the Puzzle Plank Galaxy, they are used to battle the boss Bugaboom. The Cloudy Court Galaxy introduces the fact that Mario's clouds will be affected by wind (and thus will move). In both the Starshine Beach Galaxy and Throwback Galaxy requires Mario to use the Cloud Flower to collect Silver Stars, and in Bowser Jr.'s Boom Bunker Cloud Mario is needed to defeat Bowser Jr. In Bowser's Galaxy Generator, Cloud Mario will be used, up until he acquires Yoshi. Cloud Mario is also used to collect multiple Green Stars in some of the aforementioned galaxies, along with in the Twisty Trials Galaxy. The Cloud Flower is also the only power-up that is used in the game's final galaxy, the Grandmaster Galaxy. In that galaxy's daredevil run, Cloud Mario will be kept up until the end, as there is no water or other power-ups, Cloud Mario does not disappear when in contact with a Launch Star, and if Mario takes damage, he dies and will have to restart the whole level.

Due to the fact that the Cloud Flower is the most-used power-up and the only one to be used in the Grandmaster Galaxy, it seems that the Cloud Flower is Super Mario Galaxy 2's main power-up (as Yoshi is not necessarily a power-up).