When Hail is used, a hailstorm will begin on the field. This effect will last for 5 turns. This clears any other type of weather.
While Hail is in effect, all Pokémon not of the Ice type will be damaged for 1/16 of their maximum HP at the end of each turn. Synthesis, Morning Sun and Moonlight will recover only ¼ of the user's maximum HP. Additionally, Castform and the move Weather Ball become Ice-type.
Pokémon with the Ice Body Ability recover 1/16 of their maximum HP each round. Pokémon with the Snow Cloak Ability increase their evasion by 20%. Pokémon with the Slush Rush Ability have their speed doubled. If an Icy Rock is held by the Pokémon using Hail at the time of use, the duration of Hail will increase from 5 to 8 turns.
Froslass's body glows light blue and it floats into the sky. Then, thick clouds appear above the battlefield and a thick fog forms. Froslass then floats into the clouds. Snow starts to fall from the clouds, and occasionally large balls of hail fly down and hit the opponent repeatedly. When Froslass takes a lot of damage, the clouds fade away and disappear.