There are 4 abilites affected by Snow (called Hail before Gen IX)
•Ice Body: Restores 1/16th of a Pokémon's health every turn.
•Slush Rush: Doubles the Pokémon's Speed stat.
•Snow Cloak: Moves used against the Pokémon have a 20% decrease in accuracy. When a Pokémon with Snow Cloak is at the front of your party in a snowy area, encounter rates for wild Pokémon are cut by 50%.
•Ice Face: Changes Eiscue from its No-Ice Form to its Ice Form when sent out into a battle with snow, or when a snowstorm is summoned in battle. Ice Form protects it from Physical Moves, but it will lose the Form when hit by one.