Phys.Def (Clefairy) @ Eviolite
Ability: Magic Guard
EVs: 252 HP / 252 Def / 4 SpD
Bold Nature
IVs: 0 Atk
- Soft-Boiled
- Calm Mind
- Moonblast
- Fire Blast / Stealth Rock

Sp.Def (Clefairy) @ Eviolite
Ability: Magic Guard
EVs: 252 HP / 4 Def / 252 SpD
Bold Nature
IVs: 0 Atk
- Soft-Boiled
- Calm Mind
- Moonblast
- Fire Blast / Stealth Rock

Stored Power (Clefairy) @ Eviolite
Ability: Magic Guard
EVs: 216 HP / 252 SpD / 44 Spe
Calm Nature
IVs: 0 Atk
- Soft-Boiled
- Stored Power
- Cosmic Power / Calm Mind
- Toxic / Moonblast

Set Detail & Moves: Phys.Def and Sp.Def Clefairy are both used similarly as bulky tanks however they are not to be used in front of similar threats. Clefairy has the advantage of hitting Fighting-, Dark- and Dragon-Types super effectively thank to STAB, but it doesn't always mean it can counter them. Phys.Def Clefairy is mainly used to counter Physical Attackers such as Gurdurr and Sliggo while Sp.Def Clefairy is used to counter the likes of Electabuzz and Special Monferno. Soft boiled is Clefable's most reliable recovery move due to it's higher amount of PP, it is used to recover Clefable's health when lowered as well as a reliable move to scout the opponent's move when unsure. Magic Guard allows Clefairy to set up with Calm Mind without worrying about getting Toxic'd. Moonblast allows Clefairy to hit super effectively Dark- and Fighting- types while Fire Blast is used to hit incoming Steel- and Grass-types who may resist Moonblast such as Gloom and Ferroseed. Clefairy can also be used as a hazard setter by using Stealth Rock to chip the opponent's team. 

Stored Power Clefairy however is used in a slight different way. This set is based around Stored Power, a move where as you gradually increase your stats, so will the move, once above +6 you will be able to ohko threats like Monferno and Haunter while taking nothing from them. Cosmic Power allows you to increase you Phys.Def and Sp.Def enabling Clefairy to tank incoming Poison Jab from threats such as Gurdurr and winning against it 1v1, however Calm Mind may also be an option for higher damage output. Toxic is used to cripple walls who may try to stop Clefairy from setting up while Moonblast refrains yourself from getting walled by Dark-Types. Full investment in Spdef allows you to tank hits from Haunter with more ease, while 44 Spe investment allows you to outspeed Gurdurr. 

Other Options: Clefairy can also be run counting Heal Bell and Wish to support its team mates when statu'd or at low health. 

Threats & Counters:

Poison Types such as Haunter, Gloom, Mareanie and Alolan Grimer can easily tank Clefable's STAB while striking harder. Clefable must watch out for Alolan Grimer when not running STAB as it is immune to Stored Power. All however have trouble breaking it once boosted through Calm Mind or Cosmic Power. Mareanie can also stop Clefairy from boosting itself thank to Haze. 

Steel Types such as Klang, Ferroseed and Pawniard can easily pressure Clefable with their STAB however they must watch out for Fire Blast.