Purimpopoie:
The effect of King's Rock is separate from the additional effect of attacks such as Bite. The ability Serene Grace will not double the chance to flinch: "If the user holds a King's Rock ... the opponent may flinch after the user uses this attack and this attack is successful (a 10% chance). This is considered an additional effect for the purposes of Shield Dust, but not for the purposes of Serene Grace."
The effect of King's Rock is separate from the additional effect of attacks such as Bite. The ability Serene Grace will not double the chance to flinch: "If the user holds a King's Rock ... the opponent may flinch after the user uses this attack and this attack is successful (a 10% chance). This is considered an additional effect for the purposes of Shield Dust, but not for the purposes of Serene Grace."