Project Threats to OU Cores v2: Round 72: Mega Charizard X + Ash-Greninja

[wadusher]

Kyurem-Black @ Icium Z
Ability: Teravolt
EVs: 252 Atk / 4 SpA / 252 Spe
Naive Nature
- Freeze Shock
- Fusion Bolt
- Ice Beam
- Substitute / Earth Power

Hardly anything walls this beast, meaning once you switch in on tangrowth you can freely nuke something with Subzero Slammer. Which can very easily remind Celesteela that it is, in fact, NOT an ice resist as you deal 90% to it. You can even sub up on its attempts to waste your Z move with protect.

calcs

252 Atk Teravolt Kyurem-Black Fusion Bolt vs. 248 HP / 104+ Def Celesteela: 214-254 (53.9 - 63.9%) -- guaranteed 2HKO after Stealth Rock and Leftovers recovery
252 Atk Teravolt Kyurem-Black Subzero Slammer (200 BP) vs. 248 HP / 104+ Def Celesteela: 321-378 (80.8 - 95.2%) -- 50% chance to OHKO after Stealth Rock
252 Atk Teravolt Kyurem-Black Subzero Slammer (200 BP) vs. 248 HP / 0 Def Tangrowth: 660-776 (163.7 - 192.5%) -- guaranteed Overkill
4 SpA Teravolt Kyurem-Black Ice Beam vs. 248 HP / 252+ SpD Assault Vest Tangrowth: 168-198 (41.6 - 49.1%) -- 78.9% chance to 2HKO after Stealth Rock

 

[Dreadfury]

Tangrowth+Celesteela, as a core, is incredibly weak to strong Fire-type breakers, and Blacephalon is no exception to this rule: it can run several sets that feast on Tangrowth and Celesteela alike, and unlike many of the aforementioned answers to this core Blacephalon can outright snowball when presented with a favorable matchup like this, potentially winning the game outright should either Tangrowth or Celesteela fall to its violent onslaught of Fire STAB moves.

Blacephalon @ Choice Specs
Ability: Beast Boost
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
IVs: 0 Atk
- Shadow Ball
- Trick
- Fire Blast
- Overheat

Specs Blacephalon, despite its many flaws including its status as complete Tyranitar bait, absolutely demolishes this core with Fire Blast alone:

252 SpA Choice Specs Blacephalon Fire Blast vs. 248 HP / 156 SpD Celesteela: 512-606 (128.9 - 152.6%) -- guaranteed OHKO
252 SpA Choice Specs Blacephalon Fire Blast vs. 248 HP / 252+ SpD Assault Vest Tangrowth: 434-512 (107.6 - 127%) -- guaranteed OHKO

This set's only potential switch-in is Tyranitar, as anything that can stomach two consecutive hits from this monster risks getting crippled by Trick instead. The sheer amount of pressure Blacephalon puts on this core allows it to force many switches, and with proper prediction any potential resists to Fire Blast can get devastated by Shadow Ball instead, while Chansey can lose its precious Eviolite.

Blacephalon @ Ghostium Z
Ability: Beast Boost
EVs: 232 HP / 4 Def / 20 SpA / 252 Spe
Timid Nature
IVs: 0 Atk
- Substitute
- Calm Mind
- Flamethrower
- Shadow Ball

While it doesn't demolish the core quite as badly as the Specs set, SubCM+Ghostium Blacephalon is still capable of 2HKOing both Tangrowth and Celesteela with Flamethrower. This set gets some bonus points for making Celesteela complete setup fodder for it, as without Earthquake Celesteela is unable to OHKO, let alone 2HKO, Blacephalon without Stealth Rock up. The fear of having this behemoth pick up a kill and start snowballing out of control forces many switches, which gives Blacephalon an opportunity to set up a Substitute, a Calm Mind, or potentially both and start devastating entire teams. This set fits best on Hyper Offense teams that greatly appreciate its ability to pressure things that Zygarde and Mega Gyarados can't beat 1v1 very easily, which is why it gets a shoutout.

Blacephalon @ Choice Scarf
Ability: Beast Boost
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
- Shadow Ball
- Flamethrower
- Fire Blast
- Trick

Probably the least-threatening viable Blacephalon set to this core. Scarf Blacephalon needs a bit of chip damage on Tangrowth to even have a chance to OHKO it, and it needs Stealth Rock up to solidify its OHKO on Celesteela, but it still hits hard and deserves some sort of an honorable mention.

 

[Komodo_Drogo]

Victini @ Choice Band
Ability: Victory Star
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature
- V-create
- U-turn
- Bolt Strike
- Zen Headbutt

Banded victini outspeeds and OHKOs both Clesteela and Tangrowth with Banded V-Create.

252 Atk Choice Band Victini V-create vs. 248 HP / 104+ Def Celesteela: 590-696 (148.6 - 175.3%) -- guaranteed OHKO

252 Atk Choice Band Victini V-create vs. 252 HP / 0 Def Tangrowth: 606-714 (150 - 176.7%) -- guaranteed OHKO

 

[superstrike66]

2 Attacks + Roost + DD Mega-Charizard-X

Charizard-Mega-X @ Charizardite X
Ability: Tough Claws
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature
- Dragon Claw
- Flare Blitz / Fire Punch
- Dragon Dance
- Roost

'Zard utterly destroys this core, tanking any attack they throw at 'Zard, while it OHKOs both 'mons with Blitz. Fire Punch is an option if you don't want to take recoil, but you need to Dragon Dance twice to have a guaranteed OHKO on both 'mons, so this isn't recommended (otherwise, you 2HKO both without any boosts).

Calcs:

252 Atk Tough Claws Charizard-Mega-X Flare Blitz vs. 248 HP / 0 Def Tangrowth: 422-498 (104.7 - 123.5%) -- guaranteed OHKO
252 Atk Tough Claws Charizard-Mega-X Flare Blitz vs. 248 HP / 104+ Def Celesteela: 410-486 (103.2 - 122.4%) -- guaranteed OHKO

0 Atk Tangrowth Earthquake vs. 0 HP / 4 Def Charizard-Mega-X: 132-156 (44.4 - 52.5%) -- 17.2% chance to 2HKO
0 Atk Celesteela Heavy Slam (120 BP) vs. 0 HP / 4 Def Charizard-Mega-X: 59-70 (19.8 - 23.5%) -- possible 5HKO

252 Atk Tough Claws Charizard-Mega-X Fire Punch vs. 248 HP / 104+ Def Celesteela: 258-306 (64.9 - 77%) -- guaranteed 2HKO after Leftovers recovery
252 Atk Tough Claws Charizard-Mega-X Fire Punch vs. 248 HP / 0 Def Tangrowth: 266-314 (66 - 77.9%) -- guaranteed 2HKO
+1 252 Atk Tough Claws Charizard-Mega-X Fire Punch vs. 248 HP / 104+ Def Celesteela: 386-456 (97.2 - 114.8%) -- 81.3% chance to OHKO after Leftovers recovery
+1 252 Atk Tough Claws Charizard-Mega-X Fire Punch vs. 248 HP / 0 Def Tangrowth: 396-468 (98.2 - 116.1%) -- 87.5% chance to OHKO

 

[Ultra Jiren]

Reuniclus @ Leftovers
Ability: Magic Guard
EVs: 252 HP / 212 Def / 44 Spe
Bold Nature
IVs: 0 Atk
- Psyshock
- Acid Armor
- Recover
- Calm Mind

neither tang or steela cant really touch it and it sets up on both. thanks to magic guard steelas leech seed does nothing

 

[Deleted User [433215]]

Sableye @ Sablenite
Ability: Prankster
EVs: 248 HP / 8 Def / 252 SpD
Careful Nature
- Knock Off
- Will-O-Wisp/Toxic
- Recover
- Protect

This thing walls both Tangrowth and Celesteela and threatens both with either a burn, a loss of their item, or in Tang’s case, toxic. It bounces back Celesteela’s leech seeds and isn’t 2hkod by heavy slam, not even after stealth rock.

 

[SBPC]

Pelipper @ Damp Rock
Ability: Drizzle
EVs: 100 HP / 252 SpA / 156 SpD
Modest Nature
- Hurricane
- Scald
- Roost
- Knock Off

Pelipper can threaten the core of Celesteela + Tangrowth by being able to come in on both of the mons in the core reliably, resisting or taking neutral damage to all attacks within the set, and easily roosting the damage taken off. Hurricane can bash through tangrowth, 2hkoing through his assault vest, while Scald can beat up on celesteela, having a chance to 3hko it and being able to recover all lost health with relative ease. Both pokemon struggle to switch in, due to taking a strong attack or losing their item to knock off, further softening them.

 

[Mellow]

Heracross @ Heracronite
Ability: Moxie
EVs: 252 Atk / 4 SpD / 252 Spe
Adamant Nature
- Swords Dance
- Close Combat
- Rock Blast
- Pin Missile

Can be Jolly, and the last slot doesn't matter - you can fairly freely setup on both and OHKO both with a +2 Close Combat.

calc

+2 252+ Atk Heracross-Mega Close Combat vs. 248 HP / 104+ Def Celesteela: 451-532 (113.6 - 134%) -- guaranteed OHKO
+2 252+ Atk Heracross-Mega Close Combat vs. 252 HP / 28 Def Tangrowth: 453-534 (112.1 - 132.1%) -- guaranteed OHKO

 

[Failure999]

Tangrowth is capable of checking the Electric-types that Celesteela is weak to, mainly Tapu Koko

I'm here to challenge that!

I Can Do Anything! (Tapu Koko) @ Flyinium Z
Ability: Electric Surge
EVs: 252 Atk / 4 Spa / 252 Spe
Naughty Nature
- Wild Charge
- Brave Bird
- U-Turn
- Hidden Power [Ice]

The Damage Calcs will show, but this set can help lure and trick many pokemon that feel that they are safe switch-ins to Tapu Koko and knock them out of the running. This is useful for pokemon like Ash-Gren, who would love to have its checks knocked out from the match-up, so as to sweep back the opposing team fine.

The Power of Meme Sets against this Core

252+ Atk Tapu Koko Supersonic Skystrike (190 BP) vs. 248 HP / 0 Def Tangrowth: 344-406 (85.3 - 100.7%) -- 81.3% chance to OHKO after Stealth Rock (Set up hazards with help from teammates like Landorus-Thedian and Ash-Greninja, and you should be fine)

252+ Atk Tapu Koko Brave Bird vs. 248 HP / 0 Def Tangrowth: 218-258 (54 - 64%) -- guaranteed 2HKO after Stealth Rock

252+ Atk Tapu Koko Wild Charge vs. 248 HP / 104+ Def Celesteela in Electric Terrain: 356-422 (89.6 - 106.2%) -- guaranteed OHKO after Stealth Rock and Leftovers recovery

The Power of Meme Sets against other matchups

252+ Atk Tapu Koko Brave Bird vs. 248 HP / 36+ Def Tapu Bulu: 206-244 (60 - 71.1%) -- guaranteed 2HKO after Grassy Terrain recovery

252+ Atk Tapu Koko Supersonic Skystrike (190 BP) vs. 248 HP / 36+ Def Tapu Bulu: 326-384 (95 - 111.9%) -- guaranteed OHKO after Stealth Rock and Grassy Terrain recovery

4 SpA Tapu Koko Hidden Power Ice vs. 252 HP / 0 SpD Landorus-Therian: 204-240 (53.4 - 62.8%) -- guaranteed 2HKO after Leftovers recovery

252+ Atk Tapu Koko Wild Charge vs. 244 HP / 252+ Def Eviolite Chansey in Electric Terrain: 295-348 (42 - 49.5%) -- 86.7% chance to 2HKO after Stealth Rock

Commonly Asked Questions

Q: Won't a lack of a speed-boosting nature hurt Tapu Koko?
A: Nah, with max speed investments, he still out speed positive-natured base 110 speed pokemon, and those that do manage to out speed that are either scarf or can't do much back against it (Tornadus-Thedian and the likes)

Q: Why this set, over so many better sets?
A: I wanted Mega Charizard Y, but I was too late, so while reading up reasons for this core working, I stumbled across the above statement, and the rest is written above.

Q: Since Brave Bird against Tangrowth is only a 2HKO, won't it just switch out?
A: As I mentioned, that's why hazards from the likes of Ash-Greninja is so important, to secure KOs and prevent Tangrowth from just switching out to get rid of the hazards. Also, use U-Turn to secure momentum in case you wanna trick your opponent to thinking you're a Specs set. Use the Z-Move wisely, and you should be fine.

 

[Jordy]

Last Week's Analysis

Highlights

Threat of the Round:

All Fire-type breakers submitted do incredibly well against this core lol.

Additional Notes:

: I don't think Z-Brave Bird sets are very good, but its a decent lure for teams that rely on these type of cores so I will allow it.​

​

Round 41 Core: Zygarde + Ash-Greninja

Here are your sets

Zygarde @ Leftovers
Ability: Aura Break
EVs: 236 HP / 8 Def / 152 SpD / 112 Spe
Jolly Nature
- Thousand Arrows
- Substitute
- Toxic
- Protect / Dragon Dance

Greninja-Ash @ Choice Specs
Ability: Battle Bond
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
- Hydro Pump
- Dark Pulse
- Water Shuriken
- Spikes

• This core revolves around drawing in bulky Grass-types with Zygarde to Toxic them, allowing Ash-Greninja to pressure them better.
• Try to post only OU viable Pokémon and don't post sets specifically for this core, additionally your threat should not be complete deadweight against teams that do not feature the core of Zygarde + Ash-Greninja. Everyone have a good day!

 

[~erza]

Reserving Fini

Tapu Fini @ Leftovers
Ability: Misty Surge
EVs: 248 HP / 68 Def / 192 Spe
Timid Nature
IVs: 0 Atk
- Defog
- Moonblast
- Nature's Madness
- Taunt

Blocks Toxic thanks to Misty Surge, takes nothing from TA cause no attack investment, resists Ash-Gren double STAB and can Defog the Spikes away and threaten both with Moonblast. But sometimes you can find yourself being pressured so you need to make sure to not play it recklessly.

0 Atk Zygarde Thousand Arrows vs. 248 HP / 68 Def Tapu Fini: 82-97 (23.9 - 28.2%) -- possible 5HKO after Leftovers recovery
(Pre-Battle Bond) 252 SpA Choice Specs Greninja Hydro Pump vs. 248 HP / 0 SpD Tapu Fini: 91-108 (26.5 - 31.4%) -- 20.1% chance to 4HKO after Leftovers recovery
252 SpA Choice Specs Greninja-Ash Hydro Pump vs. 248 HP / 0 SpD Tapu Fini: 121-143 (35.2 - 41.6%) -- 81.5% chance to 3HKO after Leftovers recovery

0 SpA Tapu Fini Moonblast vs. 236 HP / 152 SpD Zygarde: 176-210 (42.3 - 50.4%) -- guaranteed 3HKO after Leftovers recovery
0 SpA Tapu Fini Moonblast vs. 0 HP / 0 SpD Greninja-Ash: 260-308 (91.2 - 108%) -- 43.8% chance to OHKO

 

[Mellow]

Lopunny @ Lopunnite
Ability: Limber
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature
- Return
- High Jump Kick
- Fake Out
- Ice Punch

Faster than both and can take a Water Shuriken from even post-transformation Ash-Greninja if healthy. You obviously OHKO Ash-Greninja with HJK, Ice Punch doesn't OHKO Zygarde but it does a shit load and Thousand Arrows doesn't even 2HKO back.

calcs

252 SpA Choice Specs Greninja-Ash Water Shuriken (20 BP) (3 hits) vs. 0 HP / 4 SpD Lopunny-Mega: 174-207 (64.2 - 76.3%) -- guaranteed 2HKO
252 Atk Lopunny-Mega High Jump Kick vs. 0 HP / 4 Def Greninja-Ash: 606-714 (212.6 - 250.5%) -- guaranteed OHKO
252 Atk Lopunny-Mega Ice Punch vs. 236 HP / 8 Def Zygarde: 288-340 (69.2 - 81.7%) -- guaranteed 2HKO after Leftovers recovery

 

[avarice]

Toxicroak @ Life Orb
Ability: Dry Skin
EVs: 4 HP / 252 Atk / 252 Spe
Jolly Nature
- Swords Dance
- Gunk Shot
- Drain Punch
- Ice Punch

Toxicroak is pretty underrated on rain teams and is pretty cool in general since it deals with Toxapex. Ice Punch hits zygarde hard asf while being typically unexpected and greninja is stopped without much effort (though after battle bond Dark Pulse 2hkos).

252 Atk Life Orb Toxicroak Ice Punch vs. 236 HP / 8 Def Zygarde: 312-369 (75 - 88.7%) -- guaranteed 2HKO after Leftovers recovery

 

[Akumeoy]

Kommo-o @ Kommonium Z
Ability: Bulletproof
EVs: 252 Atk / 4 SpA / 252 Spe
Hasty Nature
- Dragon Dance
- Close Combat
- Poison Jab
- Clanging Scales

The exact set doesn't matter; the point is that Kommo-o's Clanging Scales or Clangorous Soulblaze penetrates Zygarde's Substitute and have good odds of 2HKOing and OHKOing it, respectively; this means that Kommo-o can scare Zygarde out and set up DD or CS. Meanwhile, Kommo-o's typing lets it pivot into Greninja's Hydro Pump once so it can try to kick shit in. And, naturally, it blows both back once it hits +1/+1/+1/+1/+1.

0 SpA Kommo-o Clanging Scales vs. 236 HP / 152 SpD Zygarde: 212-252 (50.9 - 60.5%) -- 88.3% chance to 2HKO after Leftovers recovery
0 SpA Kommo-o Clangorous Soulblaze vs. 236 HP / 152 SpD Zygarde: 356-420 (85.5 - 100.9%) -- 6.3% chance to OHKO after Leftovers recovery
252 SpA Choice Specs Greninja Hydro Pump vs. 0 HP / 0 SpD Kommo-o: 110-129 (42.3 - 49.6%) -- guaranteed 3HKO

 

[Loom]

@

Ability: Chlorophyll
EVs: 248 HP / 96 Def / 164 SpD
Sassy Nature
- Giga Drain
- Sludge Bomb
- Synthesis
- Hidden Power Fire / Earthquake​

Mega Venusaur is a huge hurdle for this core to get around, being able to stall out Zygarde due to being 5HKO'D by T-Arrows, and stopping Gren by being able to eat 3 Dark Pulse's and hitting back with Giga Drain.

Calcs

0 Atk

Thousand Arrows vs. 248 HP / 96 Def

-

: 76-90 (20.9 - 24.7%) -- guaranteed 5HKO
252 SpA

Dark Pulse vs. 248 HP / 164+ SpD

-

: 151-178 (41.5 - 49%) -- guaranteed 3HKO
0 SpA

-

Giga Drain vs. 0 HP / 0 SpD

: 254-302 (89.1 - 105.9%) -- 31.3% chance to OHKO

​

 

[Dreadfury]

Gonna reserve Scarf Lele I guess.

Tapu Lele @ Choice Scarf
Ability: Psychic Surge
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
- Psychic
- Moonblast
- Focus Blast
- Hidden Power Fire

No Lele variant worth a damn would ever consider switching into either of these behemoths, but Scarf Lele does a pretty good job at doing a considerable amount of damage to this core if it gets in safely. It outspeeds and OHKOs Ash-Greninja effortlessly and Psychic Terrain outright nullifies its devastating Water Shurikens for five turns. Zygarde is a much bigger issue, however, as with that much defensive investment it even has a non-negligible chance of getting a Substitute up at some point before Lele comes in, getting a Dragon Dance up behind that Sub as Lele breaks it, and still living the Moonblast thereafter, properly ensuring that Lele has chance of being OHKOed by a +2 Thousand Arrows from full. Nevertheless, Scarf Lele deserves a bit of a nod because it can consistently outpace a +1 Zygarde, acting as a revenge killer if Zygarde is weakened beforehand and stopping the snake from barreling through your team. It also doesn't like getting hit by Toxic, but I'd personally much rather get it poisoned than risk letting Zygarde get to +2 at any point.

Specs Lele has a little more than a 25% chance of surviving Ash-Greninja's Hydro Pump from full, which is extremely unreliable, but it most certainly doesn't have the same issues with a healthy Zygarde that Scarf does. Scarf deals with this core waaaay better though.

Some calcs:
252 SpA Tapu Lele Moonblast vs. 0 HP / 0 SpD Greninja-Ash: 410-486 (143.8 - 170.5%) -- guaranteed OHKO
252 SpA Tapu Lele Moonblast vs. 236 HP / 152 SpD Zygarde: 278-330 (66.8 - 79.3%) -- guaranteed 2HKO after Stealth Rock and Leftovers recovery
+2 0 Atk Zygarde Thousand Arrows vs. 0 HP / 0 Def Tapu Lele: 246-289 (87.5 - 102.8%) -- 18.8% chance to OHKO

 

[Komodo_Drogo]

Reserving mega Garchomp

 

[wadusher]

Greninja @ Choice Scarf
Ability: Protean
EVs: 176 Atk / 80 SpA / 252 Spe
Hasty Nature
- Gunk Shot
- U-turn
- Ice Beam
- Spikes

This set just spams u-turn until something dies or Zygarde's sub breaks, and can ice beam with impunity if its sub is gone without even having to fear espeed from that set.

 

[Komodo_Drogo]

Garchomp-Mega @ Garchompite
Ability: Sand Force
EVs: 252 Atk / 116 SpD / 140 Spe
Jolly Nature
- Swords Dance
- Outrage
- Earthquake
- Fire Fang
Okay, to start off this spread is meant to outspeed the given Zygarde spread by one point, the extra speed isn't necessarily needed anymore as the common threats to it tend to outspeed it even with max investment so we can speedcreep for things such as the given zygarde spread, . While dragon claw would be the preferred move, outrage is a necessary evil in this case to have a high chance of OHKOing zygarde.

252 Atk Garchomp-Mega Outrage vs. 236 HP / 8 Def Zygarde: 408-480 (98 - 115.3%) -- 87.5% chance to OHKO after Leftovers recovery

After outspeeding and taking out zygarde, the ev investment allows Garchomp to tank a hydro pump from specs ash gren and OHKO in return with the second outrage.

252 SpA Choice Specs Greninja-Ash Hydro Pump vs. 0 HP / 116 SpD Garchomp-Mega: 280-331 (78.4 - 92.7%) -- guaranteed 2HKO

252 Atk Garchomp-Mega Outrage vs. 0 HP / 0 Def Greninja-Ash: 333-393 (116.8 - 137.8%) -- guaranteed OHKO

The only realistic way of getting this in is on a predicted zygarde protect or as an aggresive switch.

For other matchhups, it can return to the standard move set and proceed to force a switch and potentially heavily chip or ohko common checks.

Garchomp-Mega @ Garchompite
Ability: Sand Force
EVs: 252 Atk / 120 SpD / 136 Spe
Jolly Nature
- Dragon Claw
- Earthquake
- Swords Dance
- Fire Fang
With this spread, it allows garchomp to still outspeed max speed heatran while also allowing it to mostly survive scarf lele's moon blast given that it has taken no previous damage and allows it to tank a hydro pump from ash gren still. Though Switching into steelium heatran is still out of the question.

252+ SpA Heatran Corkscrew Crash (160 BP) vs. 0 HP / 120 SpD Garchomp-Mega: 264-312 (73.9 - 87.3%) -- guaranteed 2HKO

252 SpA Tapu Lele Moonblast vs. 0 HP / 120 SpD Garchomp-Mega: 288-338 (80.6 - 94.6%) -- 6.3% chance to OHKO after Stealth Rock

252 SpA Tapu Lele Moonblast vs. 0 HP / 120 SpD Garchomp-Mega: 288-338 (80.6 - 94.6%) -- guaranteed 2HKO

252 SpA Choice Specs Greninja-Ash Hydro Pump vs. 0 HP / 120 SpD Garchomp-Mega: 280-331 (78.4 - 92.7%) -- guaranteed 2HKO

Beyond the liberty of being able to play with the ev spread a bit, garchomp is somewhat difficult for teams to pivot into if it's able to get out, threatening to OHKO or heavily many common walls and checks such as tapu bulu, celesteela, heatran, toxapex, and (if a swords dance can be acquired) clefable.
(For several of these, the swords dance would most likely be acquired on a forced switch)

(Specially defensive tapu bulu)
+2 252 Atk Garchomp-Mega Fire Fang vs. 248 HP / 8 Def Tapu Bulu: 306-360 (89.2 - 104.9%) -- guaranteed OHKO after Stealth Rock, Leftovers recovery, and Grassy Terrain recovery

0 Atk Tapu Bulu Horn Leech vs. 0 HP / 0 Def Garchomp-Mega in Grassy Terrain: 136-162 (38 - 45.3%) -- guaranteed 3HKO after Grassy Terrain recovery

(Celesteela)
+2 252 Atk Garchomp-Mega Fire Fang vs. 248 HP / 104+ Def Celesteela: 280-330 (70.5 - 83.1%) -- guaranteed 2HKO after Stealth Rock and Leftovers recovery

0 Atk Celesteela Heavy Slam (120 BP) vs. 0 HP / 0 Def Garchomp-Mega: 117-138 (32.7 - 38.6%) -- guaranteed 3HKO after Stealth Rock

(Toxapex)
252 Atk Garchomp-Mega Earthquake vs. 248 HP / 8 Def Toxapex: 276-326 (91 - 107.5%) -- guaranteed OHKO after Stealth Rock and Black Sludge recovery

252 Atk burned Garchomp-Mega Earthquake vs. 248 HP / 8 Def Toxapex: 138-163 (45.5 - 53.7%) -- 93.4% chance to 2HKO after Stealth Rock and Black Sludge recovery

(Landorous-T)
+1 252 Atk Garchomp-Mega Dragon Claw vs. 252 HP / 240+ Def Landorus-Therian: 186-220 (48.6 - 57.5%) -- 54.7% chance to 2HKO after Leftovers recovery

0- SpA Landorus-Therian Hidden Power Ice vs. 0 HP / 120 SpD Garchomp-Mega: 152-180 (42.5 - 50.4%) -- 0.4% chance to 2HKO

(Clefable)
+2 252 Atk Garchomp-Mega Earthquake vs. 252 HP / 252+ Def Clefable: 351-414 (89 - 105%) -- 31.3% chance to OHKO after Leftovers recovery

0 SpA Clefable Moonblast vs. 0 HP / 120 SpD Garchomp-Mega: 182-216 (50.9 - 60.5%) -- guaranteed 2HKO

My Apologies for the long explanation, but it's not a secret that many would consider mega garchomp a waste of a mega slot (which i agree with), but after reserving it due to overlooking something, I felt that I had to provide sufficient evidence rather than just leave it be with a short explanation that many would undoubtedly question, and even with the calcs that many will still do.

 

[computeraddict92]

Tangrowth @ Assault Vest
Ability: Regenerator
EVs: 252 HP / 4 Atk / 252 SpA
Rash Nature
- Giga Drain
- Hidden Power [Ice]
- Sludge Bomb
- Knock Off

Tangrowth holds an Assault Vest to protect himself from Greninja, letting none of it's attacks come close to killing it, while Giga Drain can K.O Greninja, and deal decent damage to Zygarde. HP Ice is also able to take Zygarde out fairly quick, being a guaranteed 2HKO. Sludge Bomb lets Tangrowth to take out fairy types that could come to switch in on his Giga Drain, such as Tapu Bulu or Tapu Lele.

And now, for the Damage calcs, only for the pros.

252+ SpA Tangrowth Hidden Power Ice vs. 236 HP / 152 SpD Zygarde: 228-272 (54.8 - 65.3%) -- guaranteed 2HKO after Leftovers recovery
Comfy 2hko

 

[SBPC]

Azumarill @ Normalium Z
Ability: Huge Power
EVs: 252 HP / 108 Atk / 148 SpD
- Belly Drum
- Aqua Jet
- Play Rough
- Knock Off

Azumarill is a hilariously astonishing check to this core, with the spdef investment letting him take a little bit more punishment from greninja. Azumarill can punch holes in entire teams with aqua jet/play rough STAB combo, and this core is no exception, Aqua Jet confirms 2hkos on both mons, whereas Play Rough hits both of them into oblivion and back. Normalium Z being a full restore means that under high maintenance, you can save your hp refill for when you really need it.

Not necessary but extremely funny calc

+6 108 Atk Huge Power Azumarill Play Rough vs. 0 HP / 0 Def Greninja-Ash: 1478-1742 (518.5 - 611.2%) -- guaranteed OHKO

 

[DKM]

Magearna @ Shuca Berry / Fairium Z
Ability: Soul-Heart
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
IVs: 0 Atk
- Shift Gear
- Fleur Cannon / Ice Beam
- Thunderbolt
- Focus Blast

Most of the good threats are taken, so I'll post a set that I think is a little underrated. Magearna sets up on Zygarde and thanks to a Shuca Berry it doesn't risk being in range of Ash-Greninja's Water Shuriken. A Z-crystal is obviously fine aswell, you still live a Thousand Arrows because defensive Zygarde is pretty weak, and non Ash-Greninja's Shuriken doesn't do much either, but I believe Shuca Berry is the best option if you already have a Z-move user.

 

[Martin]

Charizard @ Charizardite X
Ability: Blaze
EVs: 252 Atk / 4 Def / 252 Spe
Jolly Nature
- Dragon Dance
- Flare Blitz
- Outrage / Dragon Claw
- Earthquake

You can’t come in on either directly, but Zard X poses as a threat to this core because it’s faster than Gren at +1 while always being faster than Zyg. It also does a really good job of just generally pressuring some common cores on the types of teams that would run this core, such as Bulu+Zygarde etc. I’d say it’s probably a good idea to carry Rachi or Latias for Healing Wish support, ‘cuz otherwise you’re much harder pressed to come in repeatedly, although ur also pretty terrible without EQ so pick your poison I guess. Maybe run Blitz+EQ+Roost but bare in mind that if u do that u no longer threaten Zygarde.

 

[Egor]

Serperior @ Choice Scarf
Ability: Contrary
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
- Leaf Storm
- Glare
- Defog / Hidden Power Fire
- Knock Off / Hidden Power Fire

Rare but viable set. You only need to bring Serp on the field safely and then click Leaf Storm several times.

 

[Ultra Jiren]

Tapu Bulu @ Leftovers
Ability: Grassy Surge
EVs: 252 HP / 4 Atk / 252 SpD
Careful Nature
- Bulk Up
- Horn Leech
- Synthesis
- Superpower

this walls ash-gren and sets up on zygarde bulk up > sd so bulu stills tanks zygarde