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>look it up on Bulbapedo
>find this:
>Until the release of Pokémon Platinum, when its pre-evolution became able to learn Bug Bite, Metapod was unable to damage Ghost-type Pokémon except by using Struggle. It shared this trait with Caterpie.
>Due to this, it was impossible to complete a Generation I game using only Caterpie or Metapod since Struggle could not hit Ghost types at the time.
