Dream Snowball Fight
From the Super Mario Wiki
Dream Snowball Fight is an event in Mario & Sonic at the Olympic Winter Games. It only appears in the Wii version of the game, but a similar event, Snow Machine Fight, appears in the Nintendo DS version.
Dream Snowball Fight has teams, with four players to a team. The goal of the game is to throw snowballs at the opponents, while trying to avoid being hit. There are also items, which makes the game similar to Mario Kart. The music is based off of the music in the winter levels of Super Mario 64.