Grass Counter
Venusaur-Mega @ Venusaurite
Ability: Chlorophyll
EVs: 248 HP / 244 Def / 16 Spe
Bold Nature
IVs: 0 Atk
- Sludge Bomb
- Hidden Power [Fire]
- Leech Seed
- Synthesis
Mega Venusaur resists just about all of the Magearna's moves and can slowly wear it down between Leech Seed and Hidden Power Fire. Without Flash Cannon, the Magearna can't 2HKO Mega Venusaur. Here's the largest amount of damage it's doing:
252 SpA Magearna Twinkle Tackle (195 BP) vs. 248 HP / 0 SpD Venusaur-Mega: 136-161 (37.4 - 44.3%) -- guaranteed 3HKO
252 SpA Magearna Fleur Cannon vs. 248 HP / 0 SpD Venusaur-Mega: 91-108 (25 - 29.7%) -- guaranteed 4HKO
That allows for an easy followup Synthesis.
Fighting Check
Terrakion @ Choice Scarf
Ability: Justified
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature
- Stone Edge
- Close Combat
- Earthquake
- X-Scissor
Not much to say here either. Choice Scarf Terrakion is capable of outspeeding Magearna even after a Shift Gear, and can pick it off with Earthquake after prior chip damage, or put it within range of Breloom's Mach Punch. Overall a nice check.
252 Atk Terrakion Earthquake vs. 0 HP / 0 Def Magearna: 192-228 (63.7 - 75.7%) -- guaranteed 2HKO
Flying Check
Zapdos @ Leftovers
Ability: Pressure
EVs: 248 HP / 188 SpD / 72 Spe
Timid Nature
IVs: 0 Atk
- Discharge
- Substitute
- Toxic
- Roost
And also...
Electric Check
Zapdos @ Leftovers
Ability: Pressure
EVs: 248 HP / 196 SpD / 64 Spe
Calm Nature
IVs: 0 Atk
- Discharge
- Heat Wave
- Defog
- Roost
I technically don't think this is against the rules or anything. Both of these Zapdos sets seen on either of its two types do a nice job at checking Magearna. They're checks since they can't switch into an unboosted Twinkle Tackle alongside the Fleur Cannon.
SubToxic Zapdos:
252 SpA Magearna Twinkle Tackle (195 BP) vs. 248 HP / 188 SpD Zapdos: 286-337 (74.6 - 87.9%) -- guaranteed 2HKO after Leftovers recovery
Defogging Zapdos:
252 SpA Magearna Twinkle Tackle (195 BP) vs. 248 HP / 196+ SpD Zapdos: 259-306 (67.6 - 79.8%) -- guaranteed 2HKO after Leftovers recovery
Fairy Counter
Magearna @ Assault Vest
Ability: Soul-Heart
EVs: 116 HP / 252 SpA / 140 Spe
Modest Nature
IVs: 0 Atk
- Fleur Cannon
- Flash Cannon
- Aura Sphere
- Volt Switch
lol Magearna counters itself. The strongest attack the Shift Gear Magearna has for the Assault Vest Magearna is a Twinkle Tackle, and even that will be doing mediocre damage at best. Meanwhile, the Magearna can either wear it down slowly with Flash Cannon or Volt Switch pivot into something that can potentially revenge kill if it hasn't gotten up any Shift Gears.
252 SpA Magearna Thunderbolt vs. 116 HP / 0 SpD Assault Vest Magearna: 59-70 (17.8 - 21.2%) -- possible 5HKO
252 SpA Magearna Twinkle Tackle (195 BP) vs. 116 HP / 0 SpD Assault Vest Magearna: 94-111 (28.4 - 33.6%) -- 0.5% chance to 3HKO
Ice Check
Mamoswine @ Focus Sash
Ability: Thick Fat
EVs: 252 Atk / 4 Def / 252 Spe
Jolly Nature
IVs: 0 HP
- Earthquake
- Ice Shard
- Endeavor
- Stealth Rock
Probably Ice's safest Magearna check, since Jolly AlolaSash will only be speed tying under Hail and can't OHKO with a Banded/Life Orb Earthquake. Mamoswine, however, actually does have an incredibly high chance to OHKO with Earthquake, and if by some miracle it does survive, it'll be picked off by the following Ice Shard.
252 Atk Mamoswine Earthquake vs. 0 HP / 0 Def Magearna: 290-344 (96.3 - 114.2%) -- 81.3% chance to OHKO
252 Atk Mamoswine Ice Shard vs. 0 HP / 0 Def Magearna: 29-35 (9.6 - 11.6%) -- possible 9HKO
Flying Check
Charizard-Mega-Y @ Charizardite Y
Ability: Blaze
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
IVs: 0 Atk
- Fire Blast / Flamethrower
- Focus Blast
- Solar Beam
- Roost
With a sun boosted Flamethrower/Fire Blast, Mega Charizard Y serves as a nice check for this Magearna set. And while it can't live a Thunderbolt after Stealth Rock, it can live one from full health.
252 SpA Charizard-Mega-Y Fire Blast vs. 0 HP / 4 SpD Magearna in Sun: 558-656 (185.3 - 217.9%) -- guaranteed OHKO
252 SpA Charizard-Mega-Y Flamethrower vs. 0 HP / 4 SpD Magearna in Sun: 458-540 (152.1 - 179.4%) -- guaranteed OHKO
252 SpA Magearna Thunderbolt vs. 0 HP / 4 SpD Charizard-Mega-Y: 174-206 (58.5 - 69.3%) -- guaranteed 2HKO
Bug Check
Volcarona @ Firium Z
Ability: Flame Body
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
IVs: 0 Atk
- Fire Blast
- Giga Drain
- Hidden Power [Ground]
- Quiver Dance
Volcarona does a fantastic job of checking Magearna with the Firium Z or simply a STAB Fire Blast, scoring a OHKO with or without a Quiver Dance under its belt. It can even take a Thunderbolt with decent health remaining.
252 SpA Volcarona Fire Blast vs. 0 HP / 4 SpD Magearna: 326-386 (108.3 - 128.2%) -- guaranteed OHKO
252 SpA Volcarona Inferno Overdrive (185 BP) vs. 0 HP / 4 SpD Magearna: 548-648 (182 - 215.2%) -- guaranteed OHKO
252 SpA Magearna Thunderbolt vs. 0 HP / 4 SpD Volcarona: 94-111 (30.2 - 35.6%) -- 33.7% chance to 3HKO
Fighting Check
Infernape @ Focus Sash
Ability: Blaze
EVs: 168 Atk / 88 SpA / 252 Spe
Naive Nature
- Fire Blast
- Close Combat
- Stealth Rock
- Taunt
While Choice Banded sets can check Magearna when it's unboosted, suicide lead Infernape checks it boosted or not when its Focus Sash is intact. It can Taunt to prevent it from setting up, and if it decides to attack, a Blaze boosted Fire Blast will always OHKO
88 SpA Blaze Infernape Fire Blast vs. 0 HP / 4 SpD Magearna: 356-420 (118.2 - 139.5%) -- guaranteed OHKO
Electric Check
Golem-Alola @ Focus Sash
Ability: Galvanize
EVs: 252 Atk / 4 Def / 252 Spe
Adamant Nature
- Return
- Stone Edge
- Explosion
- Stealth Rock
With its Focus Sash intact, Alolan Golem will guarantee its survival against any of Magearna's attacks, and unlike with Earthquake, Explosion will always OHKO even outside of Electric Terrain.
252+ Atk Galvanize Golem-Alola Explosion vs. 0 HP / 0 Def Magearna: 450-531 (149.5 - 176.4%) -- guaranteed OHKO
Dragon Check
Garchomp @ Focus Sash
Ability: Rough Skin
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature
- Outrage
- Earthquake
- Swords Dance / Fire Blast
- Stealth Rock
Despite how great bulky Stealth Rock Garchomp is on Dragon, an offensive Stealth Rocking lead set does a better job at checking Magearna. Similarly to Mamoswine, Earthquake will have the exact same chance of OHKOing Magearna. But unlike Mamoswine, it doesn't have a priority move to pick it off in case it survives, so it'll have to fall back on Scarf Latios or Extreme Speed Dragonite to finish the job.
252 Atk Garchomp Earthquake vs. 0 HP / 0 Def Magearna: 290-344 (96.3 - 114.2%) -- 81.3% chance to OHKO
Ghost Check
Chandelure @ Choice Scarf / Choice Specs
Ability: Flash Fire
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
IVs: 0 Atk
- Shadow Ball
- Fire Blast / Flamethrower
- Energy Ball
- Trick
Both Choice Scarf and Choice Specs sets can effectively check Magearna. On Scarf sets, Flamethrower won't always guarantee the OHKO whereas Fire Blast will, meaning you'll have to fall back on Mimikyu or Scarf Gengar for picking it off afterwards. Also, Chandelure can survive a Thunderbolt with decent health remaining.
252 SpA Chandelure Flamethrower vs. 0 HP / 4 SpD Magearna: 284-336 (94.3 - 111.6%) -- 62.5% chance to OHKO
252 SpA Chandelure Fire Blast vs. 0 HP / 4 SpD Magearna: 344-408 (114.2 - 135.5%) -- guaranteed OHKO
252 SpA Magearna Thunderbolt vs. 0 HP / 4 SpD Chandelure: 107-127 (40.9 - 48.6%) -- guaranteed 3HKO
Water Check
Swampert-Mega @ Swampertite
Ability: Torrent
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature
- Waterfall
- Earthquake
- Ice Punch
- Stealth Rock
Mega Swampert will have to be Jolly in order to outspeed +2 Magearna under rain. But even with Jolly, Earthquake will still always be OHKOing it. However, it won't be taking a Fleur Cannon well.
252 Atk Swampert-Mega Earthquake vs. 0 HP / 0 Def Magearna: 324-384 (107.6 - 127.5%) -- guaranteed OHKO
252 SpA Magearna Fleur Cannon vs. 0 HP / 4 SpD Swampert-Mega: 195-231 (57.1 - 67.7%) -- guaranteed 2HKO
Water Check
Kingdra @ Choice Specs
Ability: Swift Swim
EVs: 252 SpA / 4 SpD / 252 Spe
Modest Nature
IVs: 0 Atk
- Hydro Pump
- Surf
- Draco Meteor
- Ice Beam
Unlike Swampert, Kingdra won't have to be Timid to outspeed +2 Magearna under rain. Hydro Pump under rain will always be OHKOing Magearna, while Surf only has a slight chance.
252+ SpA Choice Specs Kingdra Hydro Pump vs. 0 HP / 4 SpD Magearna in Rain: 316-373 (104.9 - 123.9%) -- guaranteed OHKO
252+ SpA Choice Specs Kingdra Surf vs. 0 HP / 4 SpD Magearna in Rain: 259-306 (86 - 101.6%) -- 12.5% chance to OHKO
Bug Counter
Scizor @ Leftovers
Ability: Technician
EVs: 248 HP / 124 Def / 136 SpD
Impish Nature
- U-turn
- Bullet Punch
- Swords Dance
- Roost
Bulky Scizor can tank Magearna's hits relatively well, being able to survive a Twinkle Tackle+Aura Sphere and be able to Roost off the damage. With Swords Dance, Roost, and Bullet Punch, Scizor can either 1v1 the Magearna single-handedly, or U-turn pivot into something like Volcarona to pick it off easily.
252 SpA Magearna Twinkle Tackle (195 BP) vs. 248 HP / 136 SpD Scizor: 163-192 (47.5 - 55.9%) -- 25.8% chance to 2HKO after Leftovers recovery
252 SpA Magearna Aura Sphere vs. 248 HP / 136 SpD Scizor: 90-106 (26.2 - 30.9%) -- 5.5% chance to 4HKO after Leftovers recovery
Bug Check
Scolipede @ Life Orb
Ability: Speed Boost
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature
- Megahorn
- Earthquake
- Rock Slide / Poison Jab
- Protect
Scolipede has to be Jolly in order to outspeed Magearna with a single Speed Boost after +2. A Jolly Earthquake can pick it off after prior chip damage, or leave it within range of Scizor's Bullet Punch.
252 Atk Life Orb Scolipede Earthquake vs. 0 HP / 0 Def Magearna: 211-250 (70 - 83%) -- guaranteed 2HKO
Alright, I'm done for now, hopefully I didn't get one that you guys were planning on submitting :) (Also oml easily my largest post yet)