Looks decent but I think it's a bit passive for a stall team. As Platdude said I think mega venusaur over Gourgeist is a good place to start. You don't have a mega slot and Mega Venusaur's a better wall with more reliable recovery. It's probably the best use of a mega slot on most stall teams and will greatly increase your teams utility and general ability to win.

Venusaur (M) @ Venusaurite
Ability: Chlorophyll
EVs: 252 HP / 60 Def / 196 SDef
Relaxed Nature
- Synthesis
- Giga Drain
- Earthquake
- Sludge Bomb
You can obviously change up the spread or throw leech seed on there or whatever, anyways on to other changes. I think you could ditch SR on chansey and put it on heatran over earth power, freeing up a slot for Wish or Toxic, to support the team better, although its up to you since chansey gets a lot of SR opportunities, it's just that Heatran doesn't really need roar too much in gen 6 nor earth power since you don't hit a ton of stuff that the rest of the team doesn't beat, and most of the threats you needed to roar out last gen are gone [plus you dont have many hazards]. Assault vest Conkeldurr doesn't do a whole ton for stall teams honestly and is more suited as a utility poke for offense, I think you might want to replace it with a quagsire since it's a stellar poke this gen and gives you another physical wall to prevent anyone breaking you. I don't think you need to be worried about bisharp as you have poison heal gliscor which 'beats' knock off as long as its activated, unless you need to heal venu really badly with heal bell.

Quagsire (M) @ Leftovers
Ability: Unaware
EVs: 252 HP / 252 Def / 4 SDef
Relaxed Nature
- Toxic
- Scald
- Earthquake
- Recover