You "just" have to survive 4 turns against TR. In Unova-only with Amonguss and/or Volcarona @rage powder, some huge priority users (Conkeldurr for example), and Protect on several Poké, it should not be a problem.
And if you really have serious issues against TR, Chandelure @Imprison could be an effective answer.
In fact, TR is quite bad in Unova-only, imo.
^Oh, it's actually pretty good. They added some pretty bulky/slow pokemon this gen(like the Conkeldurr you mentioned). You just have to think about TR when you make your team in order to beat it, but that's how most double battle teams work.
Yeah, I agree with Zachmac on this one. I personally use Trick Room and I'm doing pretty ok, although I'm still 9-1.
Honestly, from the battle's I've had using this team (not in the Autumn Friendly), Trick Room works best when it's limited to Unova only. Once you've worked your way around Anti-TR teams, Unova Pokemon don't really have a good way of stopping a Trick Room. And in a double battle, where everything is almost two times as fast as in a regular battle, 4 turns is A LONG time. More than enough time to take your Pokemon down. Most of my battles end on the 5th or 6th turn.
Put a Mental Herb on your TR Pokemon, max out its defenses, and partner it with a Fake Out, and your TR can survive almost anything Unova Pokemon throw at it. At the very least, your TR Pokemon will survive long enough to use TR.
And if you're going up against a fellow TR team, allow them to set up the TR and set yourself up. I personally Reflect and Bulk Up to ensure survival, and if they don't set up TR, my Pokemon will be faster than them. This might particularly work for me only because I didn't IV breed them to the extent that I looked for the Pokemon with the least IVs in speed; I just wanted the stats I needed to have 27-31 IVs to be happy.
But Trick Rooms are pretty good, stopping TerraCott from outspeeding you and allowing you to take out that Terrakion (which is normally what'll won a match for you).
Maybe TR won't guarantee a 100% win ratio, it works well enough to keep you pretty up there (since almost everyone's trying to make their Pokemon fast.)
I have two taunters.
And if not that, Archeops can OHKO Chandalure, Reuniclus, Musharna, and Jellicent. It's also immune to EQ, and has STAB rock slide. I know, I'm biased.
Again, if it works. You'd have to waste a turn Taunting though, allowing its partner to set up OR get in a big hit against you. And if you pair with Fake Out, only one of your Pokemon will Taunt, allowing the Mental Herb to take affect and still set up TR.