When obtained in Super Mario Galaxy, Mario can turn into Ice Mario and can skate on water by creating ice pads. To create one, he must simply touch the water. If there is a little water fountain, he can hop on it to create a platform which he can use to get up ledges. This item does not make a comeback in Super Mario Galaxy 2.
In New Super Mario Bros. Wii, it is used similarly to the Fire Flower but shoots Ice Balls instead of Fireballs. Unlike the Fireballs, the Ice Balls can bounce only once. When the Ice Balls hit an enemy, they turn it into an icy platform which you can hop on. But after a while, the block of ice will break and the enemy will be freed. You can also pick up the ice block and throw it to defeat enemies, or Ground Pound it to kill the enemy inside. The Ice Flower does not freeze bosses.