Since Lore said most of the stuff, i'll say some other stuff based on what she said!
Torterra gets Rock Slide/Stone Edge by TM, so it can deal with flying types. I'd recommend one of them in place of Crunch since you got a Dark Type already.
While Night Slash has the Crit chance, Skuntank learns Crunch by breeding. 10 Base power difference, but hey... it can help. Also, Shadow Claw is somewhat redundant on it. I'd recommend Flamethrower if you keep the Naughty nature, or Poison Jab if you run an Adamant nature. You can go with Explosion too, but i don't think it's reliable anymore.
I also think that Unburden is more useful right now. Until we get those Flame Orbs, give it Unburden. I don't think there's nothing wrong with the movepool, so yeah.
Iron Head is more reliable than Iron Tail. Also, Dig is bad. Based on what i'm seeing, you're gonna get those moves by breeding, TMs or both. So Earthquake would be better. You could run Fire Punch (If we get the tutor) cuz Aggron can't do nothing to Bronzong (I doubt you're going to leave Aggron vs Bronzong anyway). Also, Adamant > Brave.
Impish would better, i agree with that. And Shadow Sneak might be good, although Gallade is weak to other ghosts, so i don't know. You can keep it if you want.
I'm pretty sure you're using stuff that you like, right? Cuz if yes, then just listen to what Lore said. It should have Fake Out and/or Return though.
If you're using Persian cuz you can't think of anything else, then i'd recommend Ambipom in place of it. Higher stats, has acess to Technician and better moves. It's superior to Persian in every way.