Here's a Cobalion set I've used that I've yet to see anyone else mention. When most people think of the Muskedeers, all they tend think about are their offensive capabilities as a sweeper. When I first I first saw Cobalion's Steel/Fighting type and 129 base defense stat, I thought defensive beast.
Nature: Careful (+Sp. Def, -Sp. Att.)
EV's: 252 Hp, 128 Def., 130 Sp. Def.
Even with no investment, 108 base speed is pretty good for a tank. The Careful nature may seem a little odd, but that slight boost in Sp. Def. can often keep it alive long enough to deliver a finishing blow. The only types you have to worry about are Fighting, Fire, and Ground; and even then only if they're of the special spectrum should you really be afraid. Works as great bait for switching in an Air Balloon-ed Chandelure or any Ghost or Flying type. Can also be brought in on a dragon locked into Outrage to set up, or on an incoming Dark type attack (ideally being Baton
Passed a few Calm Minds to shore up that Sp. Def.) to get a free attack boost. Once in place, it's pretty straight forward: throw up a Substitute to block statuses and for free Leftovers recovery while you set up, set up 3 Swords Dances, Substitute more as needed, then let the iron goat tear a path through your opponent's team. Sacred Sword bypasses any defenses they try to set up to compensate for your Sword Dances, while Stone Edge provides some much needed coverage.
Edit: EV's are for max Leftovers recovery and survivability.