Serene Grace doubles the chance of the secondary effect of moves. For example, the move Psychic, when used by the ability holder, would have a 20% chance of lowering Special Defense instead of 10%. The ability also increases the chances of certain items like King's Rock, which would have a 20% chance of flinching with the ability. Serene Grace does not work on status moves.
Game Descriptions[]
Generation III - Promotes added effects.
Generations IV - VI - Boosts the likelihood of additional effects occurring.