Damn it Smogon, why'd you unwatch me from the thread?
Let's take a look at all of Kyurem-B's generally accepted checks, and what can be run to beat them. Before we get started, we need to define counter. To me, a counter is a set/pokemon that wins against any viable variant of the given pokemon with one set, no predictions required. Does Kyurem-B have any counters? Let's find out.
As you can imagine, it goes on like this for a while, so let's talk about the few accepted "hard counters" to Kyurem-B.
Various fighting types such as Mega Blaziken, Fightinium Terrakion or Mega Heracross: Chople Berry+Outrage
So, I think it's pretty safe to say that there's no such thing as a hard Kyurem counter, even if you can get pretty close and make it have to run some weird sets to win. The only other pokemon in the history of 1v1 with no hard counters was Marshadow.
Let's take a look at all of Kyurem-B's generally accepted checks, and what can be run to beat them. Before we get started, we need to define counter. To me, a counter is a set/pokemon that wins against any viable variant of the given pokemon with one set, no predictions required. Does Kyurem-B have any counters? Let's find out.
Let's take a look at Gyarados' Kyurem matchup. This set beats the standard Icium and Scarf variants:
Gyarados-Mega @ Gyaradosite
Ability: Intimidate
EVs: 88 HP / 224 Def / 52 Spe
Adamant Nature
- Dragon Dance
- Outrage
Yay, good check! But not good enough.
Kyurem-Black @ Choice Band
Ability: Teravolt
EVs: 244 Def
Adamant Nature
- Fusion Bolt
How about we run max speed and attack with an Adamant and Jolly nature simultaneously? That'll beat the above set.
Gyarados-Mega @ Gyaradosite
Ability: Intimidate
EVs: 252 Atk / 4 Def / 252 Spe
Adamant and Jolly Natures
- Dragon Dance
- Outrage
Nevermind.
Kyurem-Black @ Choice Band
Ability: Teravolt
EVs: 216 Def / 248 Spe
Impish Nature
- Fusion Bolt
Maybe a bulky one?
Gyarados-Mega @ Gyaradosite
Ability: Intimidate
EVs: 252 Atk / 252 Def
Adamant and Impish Nature
- Dragon Dance
- Outrage
No.
Kyurem-Black @ Choice Band
Ability: Teravolt
EVs: 92 Atk / 216 Def
Impish Nature
- Fusion Bolt
Or an obese one?
Gyarados-Mega @ Gyaradosite
Ability: Intimidate
EVs: 252 HP / 4 Atk / 252 Def
Impish Nature
- Dragon Dance
- Outrage
No.
Kyurem-Black @ Choice Band
Ability: Teravolt
EVs: 232 Atk / 140 Def
Adamant Nature
- Fusion Bolt
Yeah, maybe Gyarados isn't fit for beating Kyurem-B.
Gyarados-Mega @ Gyaradosite
Ability: Intimidate
EVs: 88 HP / 224 Def / 52 Spe
Adamant Nature
- Dragon Dance
- Outrage
Yay, good check! But not good enough.
Kyurem-Black @ Choice Band
Ability: Teravolt
EVs: 244 Def
Adamant Nature
- Fusion Bolt
How about we run max speed and attack with an Adamant and Jolly nature simultaneously? That'll beat the above set.
Gyarados-Mega @ Gyaradosite
Ability: Intimidate
EVs: 252 Atk / 4 Def / 252 Spe
Adamant and Jolly Natures
- Dragon Dance
- Outrage
Nevermind.
Kyurem-Black @ Choice Band
Ability: Teravolt
EVs: 216 Def / 248 Spe
Impish Nature
- Fusion Bolt
Maybe a bulky one?
Gyarados-Mega @ Gyaradosite
Ability: Intimidate
EVs: 252 Atk / 252 Def
Adamant and Impish Nature
- Dragon Dance
- Outrage
No.
Kyurem-Black @ Choice Band
Ability: Teravolt
EVs: 92 Atk / 216 Def
Impish Nature
- Fusion Bolt
Or an obese one?
Gyarados-Mega @ Gyaradosite
Ability: Intimidate
EVs: 252 HP / 4 Atk / 252 Def
Impish Nature
- Dragon Dance
- Outrage
No.
Kyurem-Black @ Choice Band
Ability: Teravolt
EVs: 232 Atk / 140 Def
Adamant Nature
- Fusion Bolt
Yeah, maybe Gyarados isn't fit for beating Kyurem-B.
No time for tomfoolery. 3 natures, 1008 EVs.
Porygon-Z @ Choice Specs
Ability: Adaptability
EVs: 252 HP / 252 Def / 252 SpA / 252 Spe
Impish and Modest and Timid Nature
IVs: 0 Atk
- Hyper Beam
Bye.
Kyurem-Black @ Icium Z
Ability: Teravolt
EVs: 252 Atk / 216 Spe
Jolly Nature
- Freeze Shock
Porygon-Z @ Choice Specs
Ability: Adaptability
EVs: 252 HP / 252 Def / 252 SpA / 252 Spe
Impish and Modest and Timid Nature
IVs: 0 Atk
- Hyper Beam
Bye.
Kyurem-Black @ Icium Z
Ability: Teravolt
EVs: 252 Atk / 216 Spe
Jolly Nature
- Freeze Shock
Tapu Koko @ Fairium Z
Ability: Electric Surge
EVs: 252 SpA / 4 SpD / 252 Spe
Modest Nature
IVs: 0 Atk
- Dazzling Gleam
No problem.
Kyurem-Black @ Choice Specs
Ability: Teravolt
EVs: 128 HP / 252 SpD
Calm Nature
IVs: 0 Atk
- Earth Power
Ability: Electric Surge
EVs: 252 SpA / 4 SpD / 252 Spe
Modest Nature
IVs: 0 Atk
- Dazzling Gleam
No problem.
Kyurem-Black @ Choice Specs
Ability: Teravolt
EVs: 128 HP / 252 SpD
Calm Nature
IVs: 0 Atk
- Earth Power
Tapu Lele @ Psychium Z
Ability: Psychic Surge
EVs: 192 Def / 144 SpA / 24 Spe
Modest Nature
IVs: 0 Atk
- Psychic
On second thought, screw the standard, make that Fairium. Can't afford to run Modest or it loses to Jolly Icium.
Tapu Lele @ Fairium Z
Ability: Psychic Surge
EVs: 16 HP / 176 Def / 164 SpA / 152 Spe
Timid Nature
IVs: 0 Atk
- Moonblast
Nope, Lele isn't gonna work.
Kyurem-Black @ Assault Vest
Ability: Teravolt
EVs: 132 Atk / 164 SpD
Lonely Nature
- Icy Wind
- Iron Head
Ability: Psychic Surge
EVs: 192 Def / 144 SpA / 24 Spe
Modest Nature
IVs: 0 Atk
- Psychic
On second thought, screw the standard, make that Fairium. Can't afford to run Modest or it loses to Jolly Icium.
Tapu Lele @ Fairium Z
Ability: Psychic Surge
EVs: 16 HP / 176 Def / 164 SpA / 152 Spe
Timid Nature
IVs: 0 Atk
- Moonblast
Nope, Lele isn't gonna work.
Kyurem-Black @ Assault Vest
Ability: Teravolt
EVs: 132 Atk / 164 SpD
Lonely Nature
- Icy Wind
- Iron Head
Let's start aggressive with 2 natures and 756 EVs.
Charizard-Mega-Y @ Charizardite Y
Ability: Blaze
EVs: 252 HP / 252 Def / 252 SpA
Modest and Timid Nature
IVs: 0 Atk
- Blast Burn
Wow, actually had to use all of its EVs.
Kyurem-Black @ Choice Band
Ability: Teravolt
EVs: 216 HP / 48 Atk / 244 SpD
Adamant Nature
- Fusion Bolt
Charizard-Mega-Y @ Charizardite Y
Ability: Blaze
EVs: 252 HP / 252 Def / 252 SpA
Modest and Timid Nature
IVs: 0 Atk
- Blast Burn
Wow, actually had to use all of its EVs.
Kyurem-Black @ Choice Band
Ability: Teravolt
EVs: 216 HP / 48 Atk / 244 SpD
Adamant Nature
- Fusion Bolt
As you can imagine, it goes on like this for a while, so let's talk about the few accepted "hard counters" to Kyurem-B.
This set actually has lots of extra EVs. I oriented it around what it would usually need and then filled it up in bulk and special attack.
Magearna @ Choice Specs
Ability: Soul-Heart
EVs: 236 HP / 116 SpA / 252 SpD
Modest Nature
IVs: 0 Atk
- Fleur Cannon
- Flash Cannon
Yep, that just happened.
Kyurem-Black @ Psychium Z
Ability: Teravolt
EVs: 24 HP / 252 SpD
Modest Nature
IVs: 0 Atk
- Light Screen
- Earth Power
Magearna @ Choice Specs
Ability: Soul-Heart
EVs: 236 HP / 116 SpA / 252 SpD
Modest Nature
IVs: 0 Atk
- Fleur Cannon
- Flash Cannon
Yep, that just happened.
Kyurem-Black @ Psychium Z
Ability: Teravolt
EVs: 24 HP / 252 SpD
Modest Nature
IVs: 0 Atk
- Light Screen
- Earth Power
Good stuff, right?
Metagross-Mega @ Metagrossite
Ability: Clear Body
EVs: 124 HP / 252 SpD / 132 Spe
Jolly Nature
- Meteor Mash
- Bullet Punch
More Z-Screens.
Kyurem-Black @ Psychium Z
Ability: Teravolt
EVs: 24 HP / 252 Def / 32 Spe
Bold Nature
IVs: 0 Atk
- Icy Wind
- Reflect
- Roost
- Earth Power
Metagross-Mega @ Metagrossite
Ability: Clear Body
EVs: 124 HP / 252 SpD / 132 Spe
Jolly Nature
- Meteor Mash
- Bullet Punch
More Z-Screens.
Kyurem-Black @ Psychium Z
Ability: Teravolt
EVs: 24 HP / 252 Def / 32 Spe
Bold Nature
IVs: 0 Atk
- Icy Wind
- Reflect
- Roost
- Earth Power
Note: don't use Fairium, use Specs realistically. This is just for demonstration.
Tapu Fini @ Fairium Z
Ability: Misty Surge
EVs: 252 HP / 252 Def / 252 SpA / 252 Spe
Modest and Bold and Timid Nature
IVs: 0 Atk
- Moonblast
Funnee joke.
Kyurem-Black @ Roseli Berry
Ability: Teravolt
EVs: 216 Atk / 176 Spe
Jolly Nature
- Fusion Bolt
Tapu Fini @ Fairium Z
Ability: Misty Surge
EVs: 252 HP / 252 Def / 252 SpA / 252 Spe
Modest and Bold and Timid Nature
IVs: 0 Atk
- Moonblast
Funnee joke.
Kyurem-Black @ Roseli Berry
Ability: Teravolt
EVs: 216 Atk / 176 Spe
Jolly Nature
- Fusion Bolt
Gardevoir-Mega @ Gardevoirite
Ability: Trace
EVs: 40 HP / 252 Def / 216 Spe
Timid Nature
IVs: 0 Atk
- Hyper Beam
16 EVs.
Kyurem-Black @ Roseli Berry
Ability: Teravolt
EVs: 16 Atk
Adamant Nature
- Rock Tomb
- Iron Head
Ability: Trace
EVs: 40 HP / 252 Def / 216 Spe
Timid Nature
IVs: 0 Atk
- Hyper Beam
16 EVs.
Kyurem-Black @ Roseli Berry
Ability: Teravolt
EVs: 16 Atk
Adamant Nature
- Rock Tomb
- Iron Head
Seems good.
Tyranitar-Mega @ Tyranitarite
Ability: Sand Stream
EVs: 92 HP / 24 Atk / 252 Def / 140 Spe
Adamant Nature
- Rock Tomb
- Stone Edge
EV machine broke.
Kyurem-Black @ Fightinium Z
Ability: Teravolt
IVs: 0 Atk
- Focus Blast
Tyranitar-Mega @ Tyranitarite
Ability: Sand Stream
EVs: 92 HP / 24 Atk / 252 Def / 140 Spe
Adamant Nature
- Rock Tomb
- Stone Edge
EV machine broke.
Kyurem-Black @ Fightinium Z
Ability: Teravolt
IVs: 0 Atk
- Focus Blast
Terrakion @ Rockium Z
Ability: Justified
EVs: 104 HP / 252 Atk / 152 Spe
Jolly Nature
- Stone Edge
Similar set to beat Fightinium
Kyurem-Black @ Charti Berry
Ability: Teravolt
EVs: 252 SpA
Modest Nature
IVs: 0 Atk
- Icy Wind
- Earth Power
Ability: Justified
EVs: 104 HP / 252 Atk / 152 Spe
Jolly Nature
- Stone Edge
Similar set to beat Fightinium
Kyurem-Black @ Charti Berry
Ability: Teravolt
EVs: 252 SpA
Modest Nature
IVs: 0 Atk
- Icy Wind
- Earth Power
Lucario-Mega @ Lucarionite
Ability: Inner Focus
EVs: 152 Atk / 124 SpD / 232 Spe
Adamant Nature
- High Jump Kick
- Iron Tail
Kyurem-Black @ Choice Scarf
Ability: Teravolt
EVs: 124 SpA / 48 Spe
Modest Nature
IVs: 0 Atk
- Focus Blast
Ability: Inner Focus
EVs: 152 Atk / 124 SpD / 232 Spe
Adamant Nature
- High Jump Kick
- Iron Tail
Kyurem-Black @ Choice Scarf
Ability: Teravolt
EVs: 124 SpA / 48 Spe
Modest Nature
IVs: 0 Atk
- Focus Blast
Genesect @ Choice Specs
Ability: Download
EVs: 100 SpA / 184 SpD / 224 Spe
Timid Nature
IVs: 0 Atk
- Flash Cannon
Kyurem-Black @ Choice Specs
Ability: Teravolt
EVs: 80 SpA
Calm Nature
IVs: 0 Atk
- Hidden Power [Fire]
Ability: Download
EVs: 100 SpA / 184 SpD / 224 Spe
Timid Nature
IVs: 0 Atk
- Flash Cannon
Kyurem-Black @ Choice Specs
Ability: Teravolt
EVs: 80 SpA
Calm Nature
IVs: 0 Atk
- Hidden Power [Fire]
So, I think it's pretty safe to say that there's no such thing as a hard Kyurem counter, even if you can get pretty close and make it have to run some weird sets to win. The only other pokemon in the history of 1v1 with no hard counters was Marshadow.