Okay, well...I'm gonna drop this team for ya'll. Got me from 1200 to 1600 pretty consistently and after enough tweaking I believe this is the final product after about 25 or so battles. SPOILER WARNING: WORDY PARAGRAPHS!!!
https://pokepast.es/7d4a2e0b4f0b0a8e
Some notes to add:
1: This trick room team is not the slowest out there, so be on guard. Stakataka is your biggest enemy and once mag goes down, you're toast if you attempt to stop him mid-way. There are no true counters to stak and even then this team is a prime example of that. Curse Mega steelix is popping up more consistently and that's also something to be very aware of.
2: You do NOT have to keep defog on Drampa. It's a niche move and doesn't require to be there, I merely put it on because I feel it's already got both powerful stabs plus flamethrower to check Kart, Ferro, opposing Mag, and the dual attack alone invalidates sash/sturdy. If you're looking for 4 attack drampa I suggest t-bolt but coverage works too, mix and match for your desire. Sap sipper is mainly just a gimmick to keep Kart from running around and eating your team. It is not bulky, so do not rely on this as your Kart check, immediately switch to Mag at all costs. If you predict Z Smart strike, then attempt to sack another mon before bringing in Mag again.
3: Golurk is just as good a No guard mon as he is iron fist, mix and match. I suggest this set if you're looking to try the iron fist:
https://pokepast.es/cf2b93f391f40932 It's potentially the best fit for your team if you decide for iron fist but no guard works just as well and I've swapped between both, but found that under trick room, stone edge reliably hitting volc and Aero were too big of threats if left unchecked so consider no guard my personal favorite.
4: Your win con is not Mega Ampharos but goooooood lord do not underestimate it. 471 sp. attack with discharge as its first attack (breaks subs by having it as the first attack and weaker of the two, plus para chance), then follow it up with a monstrous t-bolt is too good to pass up. HP ice OhKO's any Lando that isn't running AV and dragon pulse just for stab, though you could run any number of attacks in that slot. If you get the chance to, save Mega Ampharos due to its lack of recovery, but mostly so it punches holes in the opponent's team.
5: Primarina is there mainly for coverage, but it happens to be a bulky fairy type to add to the arsenal. Moonblast/Hyper voice (or sparkling area if you prefer) just eats any Gren/T-tar/Lando/Tran that happens to think it can switch in to sponge a hit...which they never will. 383 sp. attack is nothing to sneeze at and both moves are stab 90 power. As well, be sure to experiment with the coverage moves. I barely use them but energy ball and ice beam proved to be the most useful so far.
6: Mesprit and Uxie pair well with this team for the 2nd trick room setter, just depends on if you want Memento (Uxie) or Healing wish (Mesprit), player's call. In most scenarios I find you won't be able to get them off too often so this point is somewhat moot, and I just rely on Uxie for the raw bulk it provides. But if you had to twist my arm I would rather use Mesprit's healing wish on that off chance you can get it going, so tit for tat.
7: Due to the bulk of your Mag as well as the Mesprit/Uxie you choose...I don't get discouraged when you see an Aerodactyl with taunt, or any fast taunt mon. You can freely keep volt/turning until they either decide to attack you or you keep volt-turning until you manage to get your trick room off. This can wear away at your opponent until they're pressured into attacking you regardless. Or if you're really into making reads on the guy, throw Golurk in at the start to mess him up, scare him off, double into Mag, take your pick you can do whatever you want.
8: I think this goes without saying, but the best part about running trick room is that the EV's you would normally run into speed now offer you 252 HP, something that bulks up your team quite considerably. While I sometimes see people say this is a minor point (or "DUUUUH"), the extra EV's you've slammed into HP could easily help you tank moves you otherwise wouldn't have.
Now...onto some more crucial notes...your counters...
1: Public enemy number one on this team (and most other trick room teams atm)...Stakataka. I already mentioned him earlier so I'll be brief but do not let trick room get set up until he is out of the picture. Absolutely no trick room is to be set up until then. He devours teams and once Mag is down, you have to pray you have enough sacks to outlast trick room and hope to god he cannot set it up again, or have his partners set it up.
2: Blacephalon and most common sets: Once Primarina/Drampa go down, you have to be very careful. Blace usually runs sub/flamethrower, or sub/shadow ball, and either eat your team. You can comfortably tank two +1 flamethrowers with your mega ampharos, or one +1 shadow ball, but no more. If you're able to make predictions with Drampa's normal typing as well, please do.
3: Timid Swords dance/Leaf blade Kartana: Mag goes down? You need to cherish Drampa like he was the second coming and pray he doesn't predict and go for Smart Strike. Kart mindlessly blows away Primarina, Golurk and sacred sword for Drampa. I will bet my bottom dollar most are running Steelium Z Smart Strike and they will more than likely save said Z move for your bulkiest mons, which happen to be Mag or Mega Ampharos if they're smart enough to piece that together.
4: Brave Marowak: Speed ties mega ampharos. Drampa goes down...then under trick room you're playing the final 50/50 to decide if the game's worth playing past this point or not.
5: Keys with screens, followed up with support: Klefki trolls all teams and this is no exception. Defog on drampa helps, as well as maybe running brick break on Golurk, but all of your huge threats need screens gone to deal any lasting damage. If the Keys are dumb enough to use their turn on t-waving you when you have monsters like Mega ampharos or even (heaven forbid) golurk out, then it's a no brainer that Keys are dead, but screens with light clay usually are a nuisance and should get your drampa in as soon as possible. If you can outlast it, all the more power to you.
6: Mega Charizard X with Swords dance/Flame charge or Dragon dance/Flare Blitz: Only a concern if he's set up a considerable amount of times (2 or more). Primarina with Wiki will soft check either set, though flame charge into flare blitz is risky to absorb and can usually result in you eating your wiki before you can bulk out a second bout of both hits.
Soft checks to this team that could pose a greater nuisance...but aren't THAT bad:
1: Sub/flamethrower Volcanion. Some Volcanion run Steam eruption into flamethrower/fire blast but most are running the sub/flamethrower, followed up with toxic and another coverage move, I find. Not an issue with Mega ampharos around, and setting up sub in face of Drampa is an unwise move. Even Steam Eruption/Fire blast isn't that big of a deal due to Primarina's typing and bulk tanking both hits.
2: Quiver dance/Fiery Dance Volcarona: Easily disposed of with Golurk. Cannot kill Uxie with Savage Spin-out with no boosts, and quiver into fiery dance certainly won't either. Quiver into bug buzz isn't a popular set and I haven't fought one thus far. Even so that means that if you find this set, Mag is the trick room setter you go for first, and even then (while not nearly as well), Mag will still tank a non boosted fiery dance with it's incredible bulk.
3: Zeraora...and all variations: Not nearly that big of a deal. Unless they run special defense investment, Mega Ampharos will eat all of its attacks for days, and can easily KO it back with the ironically non-absorbed electric attacks thanks to Mold Breaker. Golurk for physical bulk, absorbs electric attacks obviously...and you also have Mesprit/Uxie who will most certainly tank a +1 Plasma fist without so much as breaking a sweat.
4: Mega Lopunny: Mag...literally, Mag all the way. Eats the fakeout/poweruppunch/last resort (or Return/Frustration if you will) without so much as a scratch and sets up trick room in its face. Mega Lopunny needs to run High Jump Kick into Jump Kick to be considered a threat and I have yet to see that sort of set arise.
5: Greninja or even Ash Gren: Primarina is mainly your best counter, especially with Wiki. It's massive bulk combined with resisting both stabs lets it more often than not eat Wiki, followed up by KOing back with moonblast. If this Gren is protean, you'll have to scout for that in case of gunk shot or another set of moves, but...I haven't seen this sort of set arise and have yet to say if it's effective on this team or not.
6: Mega Aerodactyl: More often than not just OhKO'd by Golurk and can tank a +1 EQ comfortably speaking. Hone claws into stone edge will never KO Mag and even after said stone edge chip, EQ will never KO unless crit max roll, Adamant nature btw. Uxie/Mesprit have levitate and, while not nearly as well, can tank a +1 stone edge just barely.
Over the course of my laddering, I offer you these solid points. I know this team is not perfect and can easily be tweaked to anybody's liking, but as of the last 10 out of 25 battles my team has stayed the same as the pokepaste above with no changes. Enjoy if you will.