Well, I don't have a whole lot of experience with Trick Room in NU, but I'm going to go ahead and answer anyway. Hope my suggestions are useful. And I like what you've done with the nicknames. :3
Okay, firstly, Duosion. You already have another, much more powerful Psychic type trick room setter in Beheeyem. Also, Duosion is not the most bulky pokemon out there even with Eviolite, and you are not abusing one of the best abilities in the game, Magic Guard. Audino is a great replacement, giving you a Ghost immunity, a bulky special wall, and a much needed cleric and wish passer. Go with:
Audino (F) @ Leftovers
EVs: 252 HP / 252 SDef / 4 Def
Calm Nature (+SDef, -Atk)
- Trick Room
- Heal Bell
Torkoal looks fine, not sure how much it benefits your team, but it's okay.
Now Gurdurr. Ever heard of the amazing ability Guts? Gurdurr has it. Not only does it protect you from Will-O-Wisp but it gives you the same power as a Choice Band while still being able to switch moves. Go with that, and the moveset looks fine.
Okay, onto Marowak. In my opinion, Lightningrod is the best ability because it can provide him with a much needed special attack boost...just kidding. Rock Head is great, because it lets him abuse a recoil-free Double Edge. That is a better choice than Fire Punch, as his STAB Earthquake already hits steel types (except Bronzor but who uses him?). Also, Marowak with a Thick Club reaches 568 attack, so a Swords Dance is pretty redundant. Give him Substitute instead, it protects him from burn, and most importantly keeps his item from being Tricked away or Knocked Off, which kind of cripples him.
Octillery looks great. However, he is one of the lucky pokemon to get Water Spout, which is mind-blowingly powerful after STAB. As Water/Grass/Ice coverage is all you really need in NU, consider it over Flamethrower (as cool as it is that he learns it)
Beheeyem looks good as well. I know Trachy persuaded you to go HP Ground, but it does leave you walled by Exeggutor who can be a pain with his Sleep Powdering antics. Also, I haven't seen a whole lot of Skuntank in NU lately. I always go Bug or Fighting, but Ground works too. Anyway, that's me done, hope you enjoyed :)