Other Options:
Sunny Day + Flamethrower/Fire Blast, Rain Dance + Damp Rock, Return, Shadow Claw, Payback + Brave nature + 0IV Spd, Haze, Defog, Pursuit, Sucker Punch
If you're really worried about the likes of Ferrothorn and Forretress coming in and walling you, you can opt for Sunny Day and Flamethrower or Fire Blast to hit them for supereffective damage.
Rain Dance could be useful on a Rain Team with a Damp Rock to keep the Rain up for 8 turns, whilst using Memento for an easy suicide switch.
Return can be useful if you're worried about anything that isn't Steel, Rock or Ghost switching in on you and you can't hit them for at least 1x damage with anything else.
Shadow Claw just for those annoying Gengars who wall your Poison Jab, but you should be using Crunch there.
Payback with the Brave Nature means that you can hit a lot of things hard...er than if you were using Crunch or Sucker Punch, but this is situational.
Haze and Defog are now legitimate together, which means that behind a sub, you could make yourself a nuisance, but once again, you've not got enough speed to utilise it properly
Pursuit requires too much prediction, and it's half as strong as your other options.
Sucker Punch could be good, and Skuntank's attack doesn't stop it hurting something, but other users do it better.
Double and Triples Options:
Nothing different from Singles, and if anything, it's worse in Doubles/Triples
Counters:
Are you a Steel Type? Do you have Earthquake? Do you hit harder than a snail? Truth be told, it's not phenomenally difficult to counter Skuntank, but because it can run so many different sets, including the odd Sunny Day + FT/FB set, it's often a good idea to be wary. Ferrothorn and Forretress will gladly eat up Skuntank's moves, and even in the Sun, Mega Scizor survives a Flamethrower with no Sp.Atk investment and does 57% with U-turn, and considering that the Flamethrower set will barely exist, it's not worth worrying too much about. Equally, if you have base 85 Speed or above, you'll outspeed an Adamant or Brave Skuntank with no Speed investment, and if you can hit it for neutral (and everything hits it), then you can do some pain. Heck, even Mega Ampharos does 78.5% damage with Dragon Pulse. Skuntank isn't hard to counter, but he isn't easy either, with his movepool.