This is my best trick room team on showdown yet... at least I think it is :}
https://pokepast.es/ac661365c46b0e42
The team is based around two heavy hitters with massive offensive power, bulk to spare, and a speed stat low enough to exploit with trick room!
Hatterene
This mon is a fantastic lead for any trick room team, but especially this one. Sash help to guarantee trick room is set. Healing wish is always fantastic to get off as it helps to restore the bulky bois later in the match. Mystical fire is a counter to Scizor and Kartana early in the match if they get sent out as a lead for whatever reason. Misty explosion is a great way to deal with Hydreigon leads, or really any dark, dragon, or fighting type that isn't insanely bulky, at the cost of yourself of course.
Copperajah
An underrated mon due to its speed tier in regular OU, but on a trick room team this guy's coverage ability and power is fantastic. The ability Heavy Metal doubles the weight of a mon making moves like Heat Crash and Heavy Slam maximize their potential power. Earthquake is a absolute must have on almost ANY team regardless of the setup because I mean it's Earthquake... duh. Power Whip is a move for more coverage against Quagsire and Gastrodon stall, as well as an answer to Swampert-Mega, all of which are biggg counters to this team.
Mimikyu
Mimikyu is probably the best late game trick room setter in the game thanks to its ability. I have clutched so many games simply by letting this guy get a guaranteed trick room off and letting this thing get a hit off and then dying, and switching into a whittled down offensive mon that gets healed up fully by Healing Wish from Hatterene. Wooden Hammer is here for that coverage against Water/Ground types this team struggles against mostly because absolutely no one remembers/knows this mon gets Wood Hammer allowing to pretty much always work. Play Rough and Shadow Claw for STAB chip really.
Melmetal
An absolute beast in any format simply because it refuses to die and only accepts the enemies obliteration. Trick Room simply allows this to do it a little faster. This thing walks like Wide Putin so I thought hey why not base this entire post on that. Double Iron Bash destroys everything in it's path so do not use it with caution. Superpower, Ice Punch, and Thunder Punch are here for the best of coverage. I chose Electrium Z to get rid of those pesky Flying types like Corv and Skarmory, as well as deal with a water type rain abusers.
Porygon2
This mon is just here to be my bulky pivot and trick room setter during the match. Teleport helps to prevent the switch in from getting damaged. I opted for Tri Attack for STAB damage and Ice Beam for a little more coverage, especially against Garchomp and Lando-T which for some reason in my experience never see it coming and end up getting OHKOd.
Mega Camerupt
An absolute monster which has absolutely no excuse to not as underused as much as it is. Sheer Force on something with as much offensive power is simply a match made in heaven. Earth Power and Flamethrower are able to OHKO a surprising amount of things you normally see and 2HKO almost everything else. Hidden Power Electric is something few people expect and help get to get rid of those pesky Pelippers and other flying/water types people have saved. I opted for Flash Cannon for the final move because it gets a boost from Sheer Force as well as decent coverage on fairy types.
Threats:
Rain Teams is either super easy to deal with or you get your butt kicked depending on how you use the team.
Stall is something I've struggled with using this team but I have encountered it so rarely it doesn't apply as much.
Sun Teams are rare but can be a threat if you are not careful.
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Please give me some feedback on how I can use better this team!
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(if you intend to keep Porygon) or 
(if you decide to go Cress)
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Daunt can be another option, as cress helps alleviate the ground weakness, so bulu isnt needed as much, and daunt basically provides free kills every time room goes up.
, personal preference but i feel Melm appreciates the orb support much more as a boost to its other moves, rather than just electrium.
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Gives you a Melmetal 2.0 basically, and under TR doesnt have any checks, compared Mega Camel, but camel works as well, just preference tbh, but if you do stick to camel, i would change the moves to: