Thrash inflicts damage over 2-3 turns. PP is deducted only on the turn Thrash is first called. Once called, even if the move misses, the user will only be able to use Thrash, and will not be able to switch out. After Thrash is finished, the user becomes confused.
If Thrash's duration is disrupted it will immediately end. It is disrupted if it is not successful due to missing, sleeping, paralysis, freeze, flinching, a Protected target, or a type immunity. If a disruption occurs on what would have been the final, confusion-inducing turn of Thrash, the user will still become confused.
In battles with multiple opponents, the user selects itself as the target, but hits an adjacent opponent that is selected at random upon each use of the move.
Pokémon that learn Thrash
By leveling up