Politoed- I would replace refresh with Toxic or Encore, Toxic to stall, Encore to catch an opponent setting up entry hazards or trying to set up.
Stunfisk- Gliscor should work as a replacement right? Ground immunity, still has electric immunity, and can run Swords Dance. If you use its DW ability, PSN Heal, it can become immune to status as well.
Snorlax- Well I looked around at Serebii and Smogon for movesets, and I agreed with both of them; Body Slam is needed on a rest or curse user. A solid STAB move that may paralyze works amazingly. If you insist on running Curse still, run it. Just keep in mind it gets walled by ghosts and steels. Other wise, you may want to replace Curse with Crunch or Whirlwind. Crunch for ghosts, Whirlwind to prevent setting up. Whirlwind seems to be the most commonly run though. Actually, the only reason I included Crunch is because your team has no entry hazards at all.
Dusknoir- I'd keep the Dusknoir, because it works for you. I don't think it would work for me because of my playing style, but it seems like it does some real damage.
If you are going to run Ferrothorn, run spikes on it. I think you'll find your team works better with entry hazards.