Say you are using a Golduck (from the Fossil set) and you use his Psybeam. Would this be a Psychic or Water attack?

A Water attack as Psyduck is a Water Pokémon. [Ed. Note: This answer can be generalized further: When a Pokémon attacks, that attack is considered to be an attack of that Pokémon's type; it's not dependent on the energy requirement.]

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