Rivalry

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.

This Pokémon inflicts 1.25× as much regular damage against Pokémon of the same gender and 0.75× as much regular damage against Pokémon of the opposite gender. If either Pokémon is genderless, damage is unaffected.