Well first of all Quagsire isn't used that much in RU (don't ask me why it's in the tier, I don't know). Secondly, you'll probably want enough Special Attack EVs to OHKO Quagsire, which would be 144 with a neutral nature and Life Orb (it's a 50% chance to OHKO after Stealth Rock). I don't really know what else you're looking to KO, so if you give me some specifics I could help. I also wouldn't really recommend Skuntank for a Quagsire lure because, like I said, Quagsire is rarely seen. Playing around on a damage calculator makes it easy to find desired EV spreads. Here's one:
http://honko.byethost8.com/manly_calc.html