Generation Iv
Snow Cloak
Raises evasion in a hailstorm.
Detailed Effect
During hail, this Pokémon has 1.25× its evasion, and it does not take hail damage regardless of type. The evasion bonus does not count as a stat modifier. Overworld: If the lead Pokémon has this ability, the wild encounter rate is halved in snow.
Pokémon With Snow Cloak
15 canonical Pokémon forms can have this Ability.

Swinub 
Piloswine
Glaceon
Mamoswine
Froslass
Vanillite
Vanillish
Cubchoo
Beartic
Cetoddle
Alolan Sandshrew
Alolan Sandslash
Alolan Vulpix
Alolan Ninetales
Articuno