Rivalry

“Boosts the power of the Pokémon's moves by 25% against targets of the same gender, and lowers it by 25% against targets of the opposite gender. The power remains the same as usual if either Pokémon's gender is unknown.”

“The Pokémon's competitive spirit makes it deal more damage to Pokémon of the same gender, but less damage to Pokémon of the opposite gender.”

“Becomes competitive and deals more damage to Pokémon of the same gender, but deals less to Pokémon of the opposite gender.”