Poison checks
Roserade @ Choice Specs
Ability: Technician / Natural Cure
EVs: 136 HP / 252 SpA / 120 Spe
Modest Nature
IVs: 0 Atk
- Grass Knot / Energy Ball
- Sludge Bomb
-
Dazzling Gleam
- filler
This can switch in on Mega-Sableye as it uses Calm Mind for the first time and doesn't mind the potential Will-o-Wisp all that much. It can then proceed to click Dazzling Gleam:
252+ SpA Choice Specs Roserade Dazzling Gleam vs. +1 252 HP / 0 SpD Mega Sableye: 166-196 (54.6 - 64.4%) -- guaranteed 2HKO
If they click Calm Mind again:
252+ SpA Choice Specs Roserade Dazzling Gleam vs. +2 252 HP / 0 SpD Mega Sableye: 124-148 (40.7 - 48.6%) -- guaranteed 3HKO
The 2HKO is not guaranteed but you do enough damage were they have a difficult time recovering back up which gives you opportunity to fish for a crit.
In case you're facing a utility Mega-Sableye with Knock-Off, you can be pretty sure it does not carry Calm Mind. Dazzling Gleam is a guaranteed 2HKO even without your Choice Specs
Grass Knot hits heavier foes such as Tyranitar, Gyarados and Suicune very hard and Technician boosts its power when used against light targets. Energy Ball is an alternative for more consistent power and to not being shit on by featherweights such as Rotom and Manaphy. Sludge Bomb is secondary STAB and has decent coverage alongside Grass STAB. Some good options for the last moveslot are Hidden Power (Ice, Fire etc.), which gets boosted by Technician to a solid 90 BP, Extrasensory to hit Poison types such as Venusaur and Tentacruel hard and Shadow Ball to hit Psychic and Ghost types as well as hitting Steel types for neutral damage. The Speed Ev's outspeed most Zapdos and the things trying to speed creep it (you can run more/less speed if you like). Natural Cure is an option over Technician to get rid of the burn from Will-o-Wisp.
Golbat @ Eviolite
Ability: Inner Focus / Infiltrator
EVs: 248 HP / 252 SpD / 8 Spe
Careful Nature
- Brave Bird
- Poison Fang
- Defog
- Roost
There are more mons who can get around Mega-Sableye's Magic Bounce with Poison Fang (Nidoqueen and Drapion for example), but Golbat can actually last throughout the match with it's good bulk and access to Roost. The idea is simple: Click Poison Fang until you badly Poison Mega-Sableye (50% chance; not too bad since you often get multiple tries). Golbat isn't terribly useful for much else in the Ghost/Dark matchup anyway so it doesn't matter all that much that you get burned while trying to poison it (it's still better than flat out losing to Mega-Sableye.)
Brave Bird is your main STAB move. Defog is for hazard removal. Roost is for recovery. Pretty straightforward stuff.
Inner Focus allows you to counter Scarf Togekiss and surprise KO Mega-Medicham and Mega-Lopunny who think they can get free damage with Fake Out. Infiltrator is useful to deal with Substitute users such as CM Keldeo and SD Hawlucha.
You can also run a Physically defensive set.
Tentacruel @ Black Sludge
Ability: Liquid Ooze
EVs: 248 HP / 224 SpD / 36 Spe
Calm Nature
- Scald
- Acid Spray
- Rapid Spin
- Haze
Tentacruel as a Mega-Sableye check is easier to fit on teams than Roserade and Golbat, but it's also more prone to being worn down. The idea is to remove Calm Mind boosts with Haze or Acid Spray, lower it's Special Defense further with Acid Spray and eventually do enough damage with Scald to force it out. The Speed EV's allow you to outspeed Adamant Bisharp. The rest is trown into Hp and Special Defense for more bulk.
