some shit i've tried lately:

Heatran @ Leftovers
Ability: Magic Bounce
EVs: 252 HP / 252 Def / 252 SpA / 252 SpD / 252 Spe
Calm Nature
IVs: 0 Atk
- Roost
- Lava Plume
- Teleport / Anchor Shot
- Entrainment / Spectral Thief / Doom Desire
people have largely stopped running ground coverage on xern and i don't see fishious rend much either, so magic bounce heatran hard counters basically every xern. magic bounce in general i think is really valuable rn bc of how common strength sap and parting shot are. mb heatran is pretty awkward overall though bc it isn't that bulky in general, so ur running a mb steel that often still loses to pult and gigas, not rly where u want to be most of the time. sometimes lava plume is annoying to switch into
Heatran @ Assault Vest
Ability: Regenerator
EVs: 252 HP / 252 Def / 252 SpA / 252 SpD / 252 Spe
Modest/Calm Nature
IVs: 0 Atk
- Lava Plume
- Doom Desire
- Nuzzle / Spectral Thief / Filler
- U-turn
this heatran is worse against ph xern and doesn't brick strength sap, but it can take on most eternatus sets and checks random uncommon shit like mewtwo and rayquaza. regen + a strong doom desire is really cool too, you can wear down a lot of more passive teams by getting this in repeatedly on things like giratina and random fat guys, setting up a dd then pivoting into ur breakers

Eternatus @ Black Sludge
Ability: Adaptability
EVs: 252 HP / 252 Def / 252 SpA / 252 SpD / 252 Spe
Timid Nature
IVs: 0 Atk
- Core Enforcer
- Sludge Bomb
- Thunder Cage
- Spore
only defensive counterplay to this is magic bounce steels. completely broken set, ban sleep etc. here's a replay of it beating ice scales zama-c:
https://replay.pokemonshowdown.com/gen8balancedhackmons-1409205027-w92pq695yzzdbjayikoez4vl7d2yfwlpw
Eternatus @ Safety Goggles
Ability: Unaware
EVs: 252 HP / 252 Def / 252 SpA / 252 SpD / 252 Spe
Calm Nature
IVs: 0 Atk
- Sludge Bomb
- Recover
Last two slots some combination of Core Enforcer / Lava Plume / Anchor Shot / Entrainment / Court Change / Spectral Thief / hazards, very versatile
funny ph xern counter that also beats most triage stuff and checks some miscellaneous setup sweepers like ph gigas. benefits a ton from the surprise factor of unaware, people try to set up in front of this all the time and u make them look very silly. run stuff to make sure xern doesn't get to spike on you switching in

Zekrom @ Toxic Orb
Ability: Poison Heal
EVs: 252 HP / 252 Atk / 252 Def / 252 SpD / 252 Spe
Adamant Nature
- Shift Gear
- Dragon Darts
- Bolt Strike
- Obstruct
+1 252+ Atk Zekrom Bolt Strike vs. -2 252 HP / 252+ Def Zamazenta-Crowned: 430-507 (110.8 - 130.6%) -- guaranteed OHKO
that's the whole joke

Yveltal @ Life Orb
Ability: Magic Guard
EVs: 252 HP / 252 Atk / 252 Def / 252 SpD / 252 Spe
Jolly Nature
- Wicked Blow
- Brave Bird
- Nuzzle
- Strength Sap
would be cool if this did more defensively, because hard to switch into but the wicked blow pp sucks and it can take a lot of prediction to make progress in a lot of matchups. if u never lose speed ties against xerneas this gets a lot better

Tyranitar @ Assault Vest
Ability: Regenerator
EVs: 252 HP / 252 Atk / 252 Def / 252 SpD / 4 Spe
Sassy Nature
IVs: 0 Spe
- Knock Off
- U-turn
- Nuzzle / Rapid Spin
- Core Enforcer
pretty effective etern/ho-oh check, also beats those random special attackers that are getting more popular lately like mewtwo, lunala, spectrier, rayquaza, blace. make sure youve got good ph xern counterplay. if they dont know you're vest you live a pixi xern boomburst easily and nuzzle it

Zamazenta @ Life Orb
Ability: Tough Claws
EVs: 252 HP / 252 Atk / 252 Def / 252 SpD / 252 Spe
Jolly Nature
- Close Combat / Low Kick
- Wicked Blow / Triple Axel / Glacial Lance
- Bolt Strike / Sunsteel Strike
- Strength Sap
zamazenta feels really underrated atm, a very effective late-game cleaner that pairs really well with doom desire/future sight or hazard stacking. the coverage choices are a little bit awkward because there's so much variety among fighting resists in this tier: wicked blow in the second slot i think gets the best overall coverage, but triple axel makes you a much more effective etern check. bolt strike hits ho-oh, golisopod, celesteela and fini, whereas sunsteel 2hkos xerneas at the cost of coverage against everything else. for some teams this is worth it, although keep in mind that bolt strike does like 40-50 to xern anyway and sunsteel doesnt ohko it. here's a game where it does stuff:
https://replay.pokemonshowdown.com/gen8balancedhackmons-1409210915-ck3lxfg5zzom8yji6y7gmktw0ct5ciwpw
Zamazenta @ Toxic Orb
Ability: Poison Heal
EVs: 252 HP / 252 Atk / 252 Def / 252 SpD / 252 Spe
Jolly Nature
- Low Kick
- Knock Off / whatever
- whatever
- U-turn / Parting Shot
pivot into zama-c or other random passive shit and just do stuff, like ph mmx last gen. knock off + purify is a funny option against ph xern and tina, and i like parting shot for etern and espeedless pixi xern. hazards and status moves go well on this. can get worn down, so consider running strength sap or making sure you have plenty of ways to pivot this in for the passive recovery

Dialga @ Adamant Orb
Ability: Steelworker / Tinted Lens
EVs: 252 HP / 252 Def / 252 SpA / 252 SpD / 252 Spe
Modest Nature
IVs: 0 Atk
- Doom Desire
- Core Enforcer
- Roost
- Teleport / Whirlwind / Dragon Tail / Nasty Plot / Nuzzle
Dialga @ Adamant Orb
Ability: Corrosion
EVs: 252 HP / 252 Def / 252 SpA / 252 SpD / 252 Spe
Modest Nature
IVs: 0 Atk
- Doom Desire
- Core Enforcer
- Slack Off
- Toxic
doom desire is sick and very slept on right now. stuff like xern and etern are really limited by it and most teams are very reliant on zama-c/ho-oh to take doom desires, and that limited range of counterplay is easy to exploit. best partners are physical breakers that beat zama-c, things like groudon, garchomp, and zamazenta all have practically no switchins with a doom desire coming down. last moveslot on dialga is a move to stop zama-c or ho-oh from sitting in front of you and eating doom desire: teleport into a breaker is the easiest option, but phasing moves, nasty plot + tinted lens, or nuzzle are all funny alternatives. removing ice scales with core enforcer is often relevant here and ive considered running lower speed to underspeed ice scales ho-oh, but i don't think that's viable

Landorus-Therian (M) @ Sharp Beak
Ability: Aerilate
EVs: 252 HP / 252 Atk / 252 Def / 252 SpD / 252 Spe
Adamant Nature
- Rapid Spin
- Strength Sap
- Precipice Blades
- Extreme Speed
i think this is largely just outclassed by ho-oh, but it has a much stronger espeed due to not needing to run boots and can beat flash fire steels. i tried body slam > espeed on this so it could threaten tina but its not worth it, the strong espeed is the only real reason this is worth using. consider jolly > ada to sap on +speed groudon maybe, do people run that?

Tapu Bulu @ Toxic Orb
Ability: Poison Heal
EVs: 252 HP / 252 Atk / 252 Def / 252 SpD / 252 Spe
Impish Nature
- Leech Seed / Strength Sap
- Spirit Break
- Spiky Shield / Filler
- Teleport
Tapu Bulu @ Leftovers
Ability: Ice Scales
EVs: 252 HP / 252 Atk / 252 Def / 252 SpD / 252 Spe
Careful Nature
- Thousand Waves
- Spirit Break
- Shore Up
- Filler
in theory tapu bulu covers palkia and groudon in one slot and does the ph fairy thing where it switches into giratina and big zyg and slow pivots on them, but in my experience it isn't bulky enough to switch into things reliably and it doesn't have much general utility due to its poor stabs and common weaknesses. ice scales is a reliable palkia check but doesn't do anything else really.

Tornadus-Therian (M) @ Sharp Beak
Ability: Aerilate
EVs: 252 HP / 252 Def / 252 SpA / 252 SpD / 252 Spe
Timid Nature
IVs: 0 Atk
- Boomburst
- Rapid Spin / Earth Power
- Nasty Plot
- Strength Sap
was inspired by using stresh's aerilate lugia and being really impressed by how strong it was despite only have 90 base special attack. just imagine how much damage we could do if we had 110 base special attack? not a lot of good flying resists in the tier and torn outspeeds neutral nature zama-c and etern, but torn is overall not bulky enough to spin or set up reliably and not strong enough to get through flying resists/ice scales mons when they do show up, so i find it to be very matchup reliant. fun but mediocre overall

Dragapult @ Choice Specs
Ability: Adaptability
EVs: 252 HP / 252 Def / 252 SpA / 252 SpD / 252 Spe
Timid Nature
IVs: 0 Atk
- Astral Barrage
- Dragon Energy
- Volt Switch
- Clanging Scales
dogshit. do not use

bulldozer (Barraskewda) @ Choice Band
Ability: Tinted Lens
EVs: 252 HP / 252 Atk / 252 Def / 252 SpD / 252 Spe
Jolly Nature
- Fishious Rend
- U-turn
- Diamond Storm / Trick
- Diamond Storm / Lunar Dance
matchup fish returns: skewda is one of the best rain abusers at the moment, heaps of teams don't have a switchin to fishious rend (you need an extremely bulky fur coat pokemon or something with desolate land. by extremely bulky i mean its a roll to 2hko +def fur coat zama-c) and this outspeeds and ohkos etern under rain. rain is quite inconsistent rn for a wide variety of reasons and i would not suggest trying to ladder with it, but if you get the right matchup with this you really can't lose.

Toxapex @ Rocky Helmet / Safety Goggles / Black Sludge
Ability: Magic Bounce / Ice Scales
EVs: 252 HP / 252 Def / 252 SpA / 252 SpD / 252 Spe
Calm Nature
IVs: 0 Atk
- Recover
- Teleport
- Entrainment
- Scald
toxapex is not bulky enough to do anything but if u need a shitty xern check that can reliably get momentum on zama-c, then pex might be the man for the job. maybe it can check palkia sometimes, idk