Trick Room is fine if you're good. Just don't make the mistake of having one garbage trick room setter like Bronzong and then five other Pokemon that are slow and bulky. Instead, it's better to have multiple users of Trick Room that are bulky and capable of doing damage, like Reuniclus. Unfortunately, very, VERY few things fit this description, mostly consisting of Reuniclus, Slowbro/King, Musharna, and Cofagrigus. And if you'll notice, they're all weak to dark and ghost, with Porygon2 pretty much your only option if you want something that's not.
Do not make the mistake of thinking you need Trick Room up at all times. All of your Pokemon are likely to be extremely bulky, they don't need to outspeed 100% of the time. Don't make a team full of slow ass Pokemon. Have at least one fast sweeper (ideally a wall breaker, because stall teams SUCK) as back up.
Priority is not that huge of an issue. Priority attacks are usually a Pokemon's weakest attack (exception being Talonflame and anything with STAB Sucker Punch,) and most trick room teams can shrug them off. The only ones that really do hurt are Sucker Punch, Scizor and Talonflame. You should also have your own priority attacks, like Mega Mawile's Sucker Punch, which are even better under Trick Room, allowing you to Sucker Punch faster (thus slower) opponents that used a priority attack, and also as a back up for when Trick Room goes down.
Trick Room really is hard to use in singles, but it's doable.
