You've certainly made a team that deserves some congratulations! Well done! On first glance, it seems you have no outstanding weaknesses. I mean, DD Scrafty could be an issue for you, seeing as it can do some mentionable damage to Hydreigon, Virizion, and Heatran. But if you're already doing well in battles than maybe it won't, plus you do have it countered with Virizion. On the topic though, you could theoretically replace Flamethrower on Hydreigon for Focus Blast if Scrafty does give your team a harder time than speculated, but I don't really foresee that happening. Maybe just test it out and see how you like it?
I could not think of a final pokemon, and eventually decided to go with Forretress. Being able to Rapid Spin away entry hazards and set up Toxic Spikes is a huge plus, not to mention being a secondary lure for Heatran with its x4 Fire weakness. Payback hits Ghosts that try to block Rapid Spin.
In all honesty, your Forretress set is just fine. There is no real flaw with it. I just wanted to suggest a change in EVs. Forretress likes 252 HP / 176 Defense / 80 Special Defense, that way, you can really exploit Forretress' defenses, and give it a good dose of physical bulk. In my opinion, investing full EVs into Special Defense just doesn't seem worth it cause, no matter what, Forretress just isn't going to take a STAB Fire Blast from opposing Heatran. However, that doesn't mean that your special variation is completely useless. It's actually extremely viable, its just depends on what kind of opponents you are facing. I also want to mention Volt Switch to you. It's excellent for eluding trappers, primarily, and good for getting Forretress out of the common switch-ins.
So, this wasn't really a rate at all. Just something for you to think about and maybe test out. You have an awesome team in the works here, I really hope it continues to work out well for you!