I'm not super experienced with TR in gen 8 but based off your post I don't think you are either. I agree that it's not exactly top tier but I disagree with your logic.TR is ABSOLUTE FUCKING GARBAGE in this metagame. I already ranted on it before, and I'm gonna rant on it again because people keep saying TR is good when it's actually not.
They switch in for free via Teleport. Slowbro and P2 are both able to set up multiple Trick Room passes per game. Alternatively Explosion or Healing Wish. But even if you somehow do have to hard switch these things are bulked out max HP. They can usually take at least one hitAnd even then it's hard to make use of those 3 turns because while the abusers (Alolan Marowak, Hatterene) have insane attacking power, bringing them in is near impossible because they aren't that bulky at all.
252+ SpA Life Orb Hatterene Psyshock vs. 4 HP / 252+ Def Eviolite Chansey: 257-304 (40 - 47.3%) -- 47.7% chance to 2HKO after Stealth RockIn the case of Hatterene, it's extremely easy to hard counter it (Chansey says hello once more).
Also Chansey is a super free switch to Marowak.
So you run enough of them that it isn't an issue. Again I'm not saying Trick Room is going to take the meta by storm but it was playable in 7th gen and it's much stronger now in a meta with a lower power level.Lastly, it's overly reliant on keeping its setters alive,
Tournament play is a different story. I don't expect to see Trick Room in SPL or anything. But surely there is a decent team composition that would work on the ladder.