hey Hawluchinations, thanks for the answer. Somehow, after some stat calculations on both pokemon's speed..
my jolly cacturne with 31IV on speed has a total of 117 speed while regular 31IV salamence with any nature, for example,
adamant, still outspeeds my cacturne. If what u said is true, then it means the opponent's salamence ..
1. has any nature that doesnt increase speed
2. his speed IV has to be less than 31