From the Super Mario Wiki
Ice Flowers are one of the many power-up items in the Mario series. This object can be found in a ? Block if Mario or Luigi is in his Super Mario or Super Luigi form. When obtained, the hero can hurl out magic Iceballs from their hands that can freeze many enemies during gameplay. This power-up appeared in New Super Mario Bros. Wii, and New Super Mario Bros. U among other appearances in other series, having the same function, except in Super Mario Galaxy, where Mario or Luigi gains a different ability. They are the frozen counterparts of Fire Flowers.
Mario & Luigi: Partners in Time
Ice Flowers made their official debut in Mario & Luigi: Partners in Time. The effects of an Ice Flower are similar to a Bros. Flower, but they allow Mario, Luigi, Baby Mario and Baby Luigi to shoot Iceballs instead of Fireballs. Ice Flowers can randomly lower the enemies' Attack, Defense, and/or Speed.
Super Mario series
Super Mario Galaxy
Ice Flowers reappear in Super Mario Galaxy, specifically in the Beach Bowl Galaxy, the Freezeflame Galaxy, and the Deep Dark Galaxy. Ice Flowers turn Mario into Ice Mario, which lets him cross cold water and lava by creating hexagonal platforms of ice wherever he steps on either surface. Additionally, instead of running, Mario can skate about the level, increasing his speed. The music accompanying the ability increases in speed until the effect of the Ice Flower ends, in effect serving as a timer.
New Super Mario Bros. Wii
Ice Flowers reappear once more in New Super Mario Bros. Wii. In this game, they function as they did in their debut game, allowing Mario, Luigi, Blue Toad and Yellow Toad to launch Iceballs that can freeze opponents. They are often found in Towers and Castles. Yoshi can grab an Ice Ball thrown by another player or an Ice Bro and spit it out. This also works for Fireballs from a Fire Flower or a Fire Piranha Plant.
New Super Mario Bros. U
Mario Party 9
Mario Tennis Open
Paper Mario: Sticker Star
Ice Flowers appear as stickers in Paper Mario: Sticker Star game for the Nintendo 3DS. When used, Mario is transformed into Ice Mario and hurtles an Ice Flower at any ground or low-altitude enemies, freezing them. If the attack depletes their HP, they shatter. This sticker also has two variants: the Shiny Ice Flower and the Flashy Ice Flower, which inflict more damage to enemies.
Mario Golf: World Tour
In Mario Golf: World Tour, Ice Flowers appear as an item shot. They let the ball freeze terrain wherever it bounces, letting players bypass water hazards.
The Ice Flower appears in volume 36 of the Super Mario-Kun, which is adapted from Mario & Luigi: Partners in Time. It becomes Baby Luigi's primary form of offense. After Commander Shroob destroys the snowman Baby Luigi had built, Baby Luigi pulls out an Ice Flower from the snowman's remains and defeats Commander Shroob and his Support Shroobs, while accidentally freezing his other three allies. He then uses a Fire Flower to melt them, scorching Mario in the process.
Super Mario Galaxy trading card description
The Ice Flowers turn Mario into his Ice Mario form, which allows him to cross bodies of water and lava! Any liquid that Mario touches while in this form turns into hexagonal platforms that he can walk on and cross great distances. Ice Mario can also freeze waterspouts and waterfalls, which allows him passage to higher elevations.
Names in other languages