The Pokémon gradually regains HP in a hailstorm.
Ice Body is an ability introduced in Generation IV. So far, 4 Pokémon have this ability.
During Hail, the Pokémon will regain 1/16 of its maximum HP at the end of each turn. The Pokémon will take no damage from hail if it otherwise would. It can be seen as a hail counterpart to Rain Dish.
Pokémon with Ice Body