I'd go for Jolly, and maybe Timid on the Snivy. The Snivy might also like a HP spread, although I couldn't begin to say which, I just know that Serperior is really lacking for coverage moves. But Samurott I'm pretty sure gets run as jolly in VGC and the rare times it shows up in RU, and I know that Jolly max speed Emboar outspeeds anything below base 120 after a single Flame Charge, which I expect would be his best set if anyone were to actually use him.