Hydration (ability)

Hydration is an ability that was introduced in Generation IV.

In battle
At the end of each turn, if it is raining, Hydration will cure the Pokémon of any non-volatile status condition. If it cures a status condition, it does so before burn or poison damage is dealt on that turn. Pokémon who are made drowsy by  will not fall asleep until after Hydration takes effect, and as such, will not be healed until the end of the next turn.

Outside of battle
Hydration has no effect outside of battle.