Snow Warning is an ability that automatically summons a hailstorm when a Pokémon with this ability enters the battlefield. The primary effect of this ability is to change the weather condition to hail, which lasts for five turns (or eight turns if the Pokémon is holding an item like an Icy Rock).
Hailstorm: Hail causes damage to all Pokémon on the battlefield that are not Ice-type, dealing chip damage equal to 1/16th of their maximum HP at the end of each turn. Ice-type Pokémon are immune to this damage.
Abilities and Moves Boost: Certain abilities and moves can take advantage of the hailstorm. For instance: