NFE Curse SpDef Debra (Sliggoo) @ Eviolite  
Ability: Sap Sipper  
EVs: 236 HP / 252 SpD / 20 Spe  
Careful Nature  
- Outrage  
- Iron Tail / Sleep Talk
- Curse  
- Rest  

NFE Offensive (Sliggoo) @ Eviolite  
Ability: Sap Sipper  
EVs: 4 HP / 252 SpA / 252 Spe  
Modest Nature  
IVs: 0 Atk  
- Draco Meteor  
- Thunderbolt  
- Sludge Wave  
- Hidden Power [Fire]
Optional Move(s): 
- Ice Beam
Optional Item(s): 
- Choice Specs
Optional Ability: 
- N/A
Optional EV/IV(s): 
- N/A
Overview: Sliggoo is a versatile Pokemon in the metagame. Its Curse set is one of the bulkiest setup Pokemon in the metagame and its offensive special set hits hard and plays off opponents expecting the Curse set. It's also one of the best Servine counters in the tier.
Curse SpDef Debra: Curse Sliggoo is capable of winning games and serves as a decent late-game wincon. When invested, Sliggoo's special bulk is incredible, allowing it to tank hits from a large majority of special attackers in the tier, such as Electabuzz, Kadabra, Haunter, Roselia, and even Frogadier. Sap Sipper also lets it wall Servine. Curse makes Sliggoo harder to revenge kill on the physical side while increasing its damage output. Rest lets it recover HP and makes it harder to break when boosted. Outrage provides a strong physical STAB attack which hits neutral targets hard after a boost or two. Iron Tail hits Fairy-types such as Clefairy and Togetic, who are immune to Outrage. Sleep Talk gives up Iron Tail in exchange for ensuring that Sliggoo does not give an opposing Pokemon two free turns while it is asleep and deters setup on a sleeping Sliggoo. 
Offensive: Offensive four attacks Sliggoo exploits people expecting the Curse set in order to hit expected switch-ins like Machoke, Mareanie, Alolan Grimer, and Pawniard hard. Draco Meteor is Sliggoo's most powerful STAB attack and hits neutral targets hard. Thunderbolt hits Flying- and Water-types such as Mareanie, Prinplup, and Staravia for good damage without incurring Draco Meteor's Special Attack drops. Sludge Wave provides good coverage for Fairy- and Grass-types like Clefairy, Servine, Quilladin, and Togetic and Hidden Power Fire hits Steel-types like Ferroseed, Pawniard, and Klang for reasonable chip.
Checks and Counters
Curse SpDef Debra: If not carrying Iron Tail, Fairy-types completely wall Sliggoo. If it is carrying Iron Tail, strong setup sweepers such as Fraxure, Monferno, and Pawniard are capable of exploiting the two free turns Sleep Talk-less Sliggoo provides to hit it hard. Steel-types such as Pawniard, Metang, and Lairon switch into both Curse sets and can hit it hard or set up on it. Machoke can also switch into Sliggoo and hit it hard. Roar users such as Quilladin can force it out. Haze users such as Mareanie, Dusclops, and Wartortle can easily come in on Sliggoo and Haze any boosts away. Physical Dragon-types such as Fraxure and Hakamo-o cannot switch into Sliggoo but can hit it hard with their Dragon-type STAB attacks.
Offensive: Specially defensive walls such as Roselia, Dusclops, and Munchlax can easily switch into any attack from offensive Sliggoo and can either threaten it out or exploit it. Bulky Steel-types like Metang and Klang can eat a Hidden Power Fire or two and threaten Sliggoo out. It is also slow and frail on the physical side and can be revenge killed by faster threats like Monferno, Fraxure, and Hakamo-o.