The best ways to deal with Sableye is to either take it out with brute force, or render it stall/setup unusable. With the introduction of Mega Sableye a counter must also be able to prevent/deal with Calm Mind setupers, narrowing down the possible counters. Nevertheless we we look into several Pokemon that can deal with Sableye.
Talonflame @ Choice Band/ Life Orb
Ability: Gale Wings
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature
- Brave Bird
- U-turn
- Flare Blitz
- Roost /Sword Dance
Due to Sableye's Prankster boosted Will-o-Wisp physical attackers have a hard time taking on Sableye. Talonflame's Fire type makes it one of the few viable physical attackers that can take it on. As such, behold:
252+ Atk Choice Band Talonflame Brave Bird vs. 252 HP / 252 Def Sableye: 223-264 (73.3 - 86.8%) -- guaranteed 2HKO after Leftovers recovery
Even with max Def Sableye is severely damaged by BB, and a SD set can easily set up on Sableye to allow a sweep. Yet, Talonflame can still be threatened by Sableye's Knock Off or Foul Play. At the same time Talonflame have issues with the bulkier Mega Sableye, so it isnt a perfect counter.
Heracross @ Choice Scarf
Ability: Guts
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature
- Megahorn
- Close Combat
- Knock Off
- Stone Edge
Heracross is about the only counter that benefit from Priority Will-O-Wisp. Guts allow it to hit Sableye incredibly hard when it "normally" should deal less damage. Behold:
252+ Atk Guts Heracross Megahorn vs. 252 HP / 252 Def Sableye: 297-351 (97.6 - 115.4%) -- 87.5% chance to OHKO
Prior damage or a single entry hazard allows Hera to demolish Sableye, and unlike Talonflame Hera isnt very damanged by Knock Off/Foul Play. At the same time another item (Choice Band/Life Orb) allow it to kill Sableye even easier. So if you need a physical attacker to take Sableye on Heracross is your guy.
Gardevoir @ Gardevoirite
Ability: Trace
EVs: 248 HP / 252 SpA / 8 SpD
Modest Nature
- Hyper Voice
- Psyshock
- Shadow Ball
- Focus Blast
Mega Gardevoir is by far the best special attacker to deal with Sableye. Its enormous SpAtk, Fairy type and Pixilate boosted Hyper Voice allows it to absolutely demolish Sableye.
252+ SpA Pixilate Mega Gardevoir Hyper Voice vs. 252 HP / 252+ SpD Sableye: 474-558 (155.9 - 183.5%) -- guaranteed OHKO
Yikes, thats alot of damage.
252+ SpA Pixilate Mega Gardevoir Hyper Voice vs. 252 HP / 252+ SpD Sableye: 330-390 (108.5 - 128.2%) -- guaranteed OHKO
Likewise the mega form isnt faring much better. Just keep in mind that after a few Calm Minds MSableye can and will take a Hyper Voice, so MGardevoir also isnt a perfect counter.
Sableye @ Leftovers
Ability: Prankster
EVs: 252 HP / 4 Atk / 240 SpD / 12 Spe
Careful Nature
- Taunt
- Knock Off
- Will-O-Wisp
- Recover
One way to deal with Sableye is to use your own. Give it enough Speed and Taunt and "normal" Sableyes become near usless, giving you switch initiative or a free Burn/lost item. However, this Sableye can't, under any situation deal with Mega Sableye. So what we have is a Pokemon that can deal with it 100% of the times under the right circumstances, but not at all under the worst.
Absol @ Absolite
Ability: Justified
EVs: 252 Atk / 4 SpA / 252 Spe
Hasty Nature
- Sucker Punch
- Swords Dance
- Flamethrower/Knock Off
- Play Rough
Finally, Magic Bounce users in general can deal with normal Sableye, but get demolished by MSableye. Enter MAbsol. With its ability and setup potential no Sableye on the planet is safe from it. Bar the slight risk of switching in Absol can easily stop any Sableye dead in its tracks.
So that is it, if you need more suggestions let me know.