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All Pokémon on the user's team that are not fainted and do not have a status condition do a 10 power typeless attack on the target. Beat Up uses base Attack and base Defense for these calculations; EVs, IVs, and Natures are irrelevant. Beat Up hits through Wonder Guard, even if the Pokémon isn't weak to Dark. If the user targets its ally in 2v2, this results in the ally beating itself up if it doesn't have a status condition.