First of all, this is obviously a well thought out, good team, so forgive me if I overlook something when rating or sound condescending (I tend to do that apparently :( ).
I'm personally questioning the wisdom of 252 HP EVs on Blissey. I don't see what they accomplish. You'd get more physical defense from 4 HP / 252 Def / 252 SpD, Bold, than from 252 HP EVs. Ideally I'd run the traditional 176 - 216 Special Defense EVs though with Calm, I always like being able to bank on Blissey no matter what. Other than that, running 80 Special Attack will guarantee a 2HKO on 0 SpD Skarmory with Flamethrower and Stealth Rock and Shed Shell, so that's a good benchmark if you want it.
I'd really think that something like Thunder Wave would be better for Blissey than Focus Blast. It cripples a few Tyranitar variants and makes many able to be handled by Swampert, and it doesn't miss. Focus Blast's laughable accuracy has always let me down, and stall is the kind of play I've always found has zero room for error. Considering your only status is Toxic Spikes, and everything from Latias to Heatran will be ignoring that, it seems like a very safe option.
Running Spikes with Toxic Spikes on Forretress initially seemed to me to be a bad idea, but considering how rarely Toxic Spikes come into play in a floating Steel metagame, it seems more productive than carrying a dedicated Tentacruel like every other stall team. My main concern is the complete lack of recovery, but I don't know if you can do anything about that. Wish doesn't fit anywhere on this team, and you'd have to give up Toxic Spikes if you want Rest.
Your team's handling of Trick in particular is worthy of praise and is basically how people have envisioned the new face of stall in DPPT will look, in my opinion.
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