Dragon Tail

Inflicts regular damage, then switches the target out for another of its trainer’s Pokémon, selected at random. If the target is under the effect of Ingrain or Suction Cups, or it has a Substitute, or its Trainer has no more usable Pokémon, it will not be switched out. If the target is a wild Pokémon, the battle ends instead.

“The target is knocked away, and a different Pokémon is dragged out. In the wild, this ends a battle against a single Pokémon.”