Ive surely faced you with this a few times, if these battle experiences seem similar.I've been running an almost identical team for months now (and was actually ranked quite high for a while) and I have to know how you effectively deal with Blissey/Chansey? Specifically Blissey with Ice Beam. I run spikes on Nattorei and Hammer Arm on Thunder Man to deal with the two and even then it can be annoying. Right now it seems like they can waltz in on 3 to 5 of your 6 members and neutralize them.
From personal experience, I have learned that this team really hates facing Specs Gastrodon. Be sure to limit the amount of times it comes in with hazards and clever switches, because it can blast away every time you bring in Starmie, and come in on Gliscor/Thundurus. Theres no changes in particular that will fix this completely but make sure to be very careful every time you see one.
I would also put Spikes on Ferrothorn over Bulldoze. Bulldoze is rarely useful and very weak, not even breaking max HP Jirachi's subs for example. Opposing Ferrothorn are difficult to switch into and being able to set up alongside them knowing you can spin later is very useful. You can also push Blissey and Ferrothorn very close to 2HKO range from Starmie with full hazards. Don't worry about Heatran and Magnezone, as long as you seed them on the switch you're golden.
The last thing I would like to point out is the annoyance of Scarftar. I often saw it being dealt with by U-Turning it as a lead with Tornadus because Politoed is faster and everything else runs the risk of being KOed. I would lower Politoed's speed IVs to lag below standard Tyranitar so you have a safer option to lead with. Running a Relaxed nature and no speed IVs will put you below standard Tyranitar, although there is some breathing room if you find a threat in between 130 speed and Sassy Tar. If you see a sand team with Rotom-W, don't lead with this because they will surely lead against you and will likely carry Volt Switch. This is a great oppurtunity to set up with Ferrothorn.
Good luck!