The user's attacks do 25% more damage to Pokémon as the same gender as the user; the user's attacks do 25% less damage to Pokémon of the opposite gender as the user. If either Pokémon has no gender, there is no change in damage.
The user's damaging attacks with beneficial secondary effects lose those effects, but have their power increased by 1.3x. (This affects Flare Blitz due to its chance of burn, but does not affect Hammer Arm, etc., as their secondary effects are detrimental.) If the attack is boosted and the user holds Life Orb, it will not receive Life Orb's recoil effect.