This is my Trick Room Gen 8 OU team
Hatterene @ Focus Sash
Ability: Magic Bounce
EVs: 252 HP / 252 SpA / 4 SpD
Quiet Nature
IVs: 0 Atk / 0 Spe
- Trick Room
- Psychic
- Healing Wish
- Mystical Fire
The main Trick Room setter and lead sash so you can setup troom and then healing wish into a offensive threat. Its the main thing that makes it good is Magic Bounce.
Porygon2 @ Eviolite
Ability: Download
EVs: 252 HP / 52 Def / 204 SpD
Sassy Nature
IVs: 0 Atk / 0 Spe
- Recover
- Ice Beam
- Teleport
- Trick Room
Back Up Trick room setter and something that's bulky to setup trick room and Ice Beam for Landorus because its everywhere, Teleport for a pivot as well.
Marowak-Alola @ Thick Club
Ability: Lightning Rod
EVs: 248 HP / 252 Atk / 8 SpD
Brave Nature
IVs: 0 Spe
- Flare Blitz
- Poltergeist
- Earthquake
- Knock Off
Marowak is one of the offensive members of my team. Lighting Rod for an electric immunity for a pokemon. I will mention later. Knock Off and Poltergeist together is not really that good but Knock Off is good in general for high damage with 100% accuracy.
Melmetal @ Choice Band
Ability: Iron Fist
EVs: 252 HP / 252 Atk / 4 SpD
Brave Nature
IVs: 0 Spe
- Double Iron Bash
- Earthquake
- Thunder Punch
- Ice Punch
The main member, if this thing is swapped into the healing wish it can sweep most things. Elemental punches for BoltBeam coverage. Earthquake and Double Iron Bash should not be needed to be explained...
Slowbro @ Heavy-Duty Boots
Ability: Regenerator
EVs: 252 HP / 252 Def / 4 SpD
Relaxed Nature
IVs: 0 Atk / 0 Spe
- Teleport
- Slack Off
- Scald
- Trick Room
Another bulky Trick Room setter who is the reason for Lighting Rod Marowak. Heavy Duty Boots because lots of pivoting and if Hatterene dies, hazards are a problem and Regenerator works nicely with Boots.
Dragalge @ Life Orb
Ability: Adaptability
EVs: 252 HP / 252 SpA / 4 SpD
Quiet Nature
IVs: 0 Atk / 0 Spe
- Sludge Wave
- Draco Meteor
- Focus Blast
- Hydro Pump
Lastly is Dragalge which was a test at first but its really good in Trick room. It can come on and deal high damage and use Draco Meteor if TRoom is about to end to snag a KO before swapping out and its a good special threat so it can beat some physical walls.
https://pokepast.es/a4b98eb72fef760b
The team link if you want to try it