The team I'm running gets demolished by Trick Room teams. I'd like to slot in one or two "Trick Room counters" to try and up my odds against the archetype. What are some good Pokemon that might help up my winrate against Trick Room?
It would depend what type of TR you're facing, but basically every good TR team to my knowledge uses at least Lunar Dance Cresselia, and Porygon 2 as setters. Sash Hatterne with a suicide move is generally the best third setter (and usually a good lead). There are a lot of potential attackers, but Marowak-A is pretty much on every TR team. The other sweepers you'll see tend to be a toss up, but Melmetal is probably the safest second option. Some other sweepers people will use are Conkeldurr, Dhelmise, Glastrier, and Azumarill.
As for some splashable options on how to deal with TR, Melmetal matches up insanely well against all the good TR setters, can give you a free 6/5 lead if the opponent tries to lead with a setter and DiB flinches. Melm KO's Hatterne through its sash, and Porygon/Cresselia pose zero offensive threat to it, allowing it to fish for DiB flinches with almost no risk. At the very least, it puts a lot of pressure on the TR team to not lead with a setter. Taunt Heatran (especially Balloon Heatran) also matches up very well against all the setters.
TR teams tend to have awful defensive synergy and extremely limited defensive switch-in options, if any, instead relying more on being willing to sack sweepers after TR ends. As such, beast-boost Pokemon that threaten most of the team put massive offensive pressure on Trick Room. TR tends to be fine with sacking Pokemon to bring their setters in, but Pokemon like Blacephalon and Kartana can threaten a sweep if the TR player opts to sack something to them, putting them between a rock and a hard place.
Screens are very potent against TR because it tends to not run Defog. So despite Alolan-Ninetails getting destroyed by most of the TR sweepers, it's surprisingly valuable against TR in general. The same goes for any other screen setter you might be using. It's very easy for a Screener to come in against a TR setter, so if you have a screen setter, make sure to abuse it as much as possible.
You often have to pivot against TR, but on the other hand, TR tends to be unable to fit in hazards, making switching easier than it could be. There is also no shortage of options in OU that can be used against various TR sweepers, including Landorus, Heatran, Zapdos, Ferrothorn, Toxapex, Corviknight, Slowbro, Tapu Fini, Dragonite, etc... In general, most TR sweepers are physical, so physically defensive spreads fare better.
Also, if you really want to give the middle finger to Trick Room teams, Crawdaunt is incredibly abusable against pretty much any TR team.