I've reached the coveted 1600 ranking, a feat no other player has ever achieved. Here's the team I used. I call it "Perfect team".
https://pokepast.es/3034b56ff154cbf8
Creature (Eternatus) @ Choice Scarf
Ability: Dragon's Maw
EVs: 252 HP / 252 Def / 252 SpA / 252 SpD / 252 Spe
Timid Nature
IVs: 0 Atk
- Dragon Energy
- Final Gambit
- Volt Switch
- Trick
Use this to kill stuff or cripple with trick. +Speed nature lets you outspeed Regieleki and +2 neutral nature Groundon, which came up clutch a decent amount of the time for me. Choice scarf guarantees the 1v1 with imposter, though their dragon energy still chips you down to like 60% if they're eviolite. Scarf might be an uncommon choice, especially compared to specs Sceptile if you're trying to spam dragon energy, but I think outspeeding everything is important when you're reliant on keeping your HP up.
Self-proof
Not Boomburst (Kyurem-White) @ Choice Scarf
Ability: Refrigerate
EVs: 252 HP / 252 Def / 252 SpA / 252 SpD / 252 Spe
Modest Nature
IVs: 0 Atk
- Boomburst
- Trick
- Heal Bell
- Clanging Scales
The name is just there to deceive your opponent, you will actually be using boomburst 99% of the time. The team has no other status control because the Magic Guarders rarely need it and the walls don't care about status that much. But if you get hit with a bunch of paralysis (or a burn on Gyrados), a cheeky heal bell off the threat of boomburst can be clutch. Clanging scales can come in handy if you predict an imposter switch in.
Improofed by Zacian
Megatron (Gyarados-Mega) @ Clear Amulet
Ability: Magic Guard
EVs: 252 HP / 252 Atk / 252 Def / 252 SpD / 252 Spe
Jolly Nature
- Jaw Lock
- Wave Crash
- Strength Sap
- Victory Dance
I stole this from someone I played against. I had been using an almost identical set, but it didn't have jaw lock so it could only force imposter to switch. Against imposter you jaw lock, strength sap enough to keep them at +0 (to make sure a crit doesn't kill you), and get yourself to +6/+6/+6 to try to sweep. I believe jaw lock is considered a primary effect and successfully traps covert cloak imposters, but I could be wrong. I did run into an imposter that could switch out, but I think it must have had shed shell. You set up on non sap-proof physical attackers, anything that relies on passive damage, or anything that relies on strength sap to stop set-up, which is a lot of stuff.
Self-proof
Homeschooled (Arceus-Ghost) @ Spooky Plate
Ability: Magic Guard
EVs: 252 HP / 252 Def / 252 SpA / 252 SpD / 252 Spe
Timid Nature
IVs: 0 Atk
- Judgment
- Secret Sword
- Strength Sap
- Nasty Plot
Classic set. With magic guard you can ignore pretty much the entire regenvest arsenal (except for nuzzle, but I don't respect paralysis anyways). Knock off is supereffective against you, but I don't think I've ever played a sap-proof knock off user, so you can sap em and be good as new. +Speed nature jumps you above neutral nature arceus, eternatus, diancie, palkia, flutter mane, and probably some other stuff.
Self-proof
Bowling Ball (Groudon-Primal) @ Assault Vest
Ability: Fur Coat
EVs: 252 HP / 252 Atk / 252 Def / 252 SpD / 252 Spe
Impish Nature
- Bitter Blade
- Mortal Spin
- Earthquake
- Knock Off
The worst set on the team. Damage sponge against anything that doesn't have water type moves, bitter blade provides less-than-ideal recovery. Nice switch in against pixilate boomburst. If your opponent can't damage you, one of these moves is probably going to accomplish something. Automatically dies against strength sap + trapping move.
Improofed by Arceus-Ghost, or just mortal spin + knock off imposter and it'll be crippled for whatever comes in next
Mrs. Unstoppable (Zacian) @ Leftovers
Ability: Ice Scales
EVs: 252 HP / 252 Atk / 252 Def / 252 SpD / 252 Spe
Careful Nature
- Knock Off
- Spirit Break
- Recover
- Salt Cure
Easy-to-use wall, salt cure + knock off are for progress, spirit break chips and reduces incoming damage, leftovers lets you not need to use recover as often.
Improofed by Arceus-Ghost
I've been hovering around 1600 after using this team for maybe a week. Here's some replays:
Maneuvering around normalize dragapult because I let arceus get too low:
https://replay.pokemonshowdown.com/gen9balancedhackmons-2614152002?p2
Opponent lost their answer to arceus:
https://replay.pokemonshowdown.com/gen9balancedhackmons-2613645455?p2
Swept by simple weakness policy stored power:
https://replay.pokemonshowdown.com/gen9balancedhackmons-2611572774?p2
Removed opponent's Gyrados answer but died to paralysis:
https://replay.pokemonshowdown.com/gen9balancedhackmons-2613425236-2xswa8c2yfhuj2jyy25l3xjgf6ttbpjpw
Opponent was a primarily stall team which is basically an auto win when you have 2 magic guards. Eternatus choice scarf paid off though:
https://replay.pokemonshowdown.com/gen9balancedhackmons-2612852935-1sufc9c70swv51ekdn17girxggry83xpw?p2
Team is weak to paralysis, offensive fairy spam since groudon gets worn down, and Simple setup. Great against imposter and stall.
You're welcome.
Update: Ran into this exact team on the ladder while trying a new team; I knew every set and I still barely pulled out the win. Granted my new team was probably very flawed, but still a great sign that this is a tough team to play against:
https://replay.pokemonshowdown.com/gen9balancedhackmons-2615069043?p2