NFE Mixed Defense Pivot (Mareanie) @ Eviolite
Ability: Regenerator
EVs: 248 HP / 76 Def / 180 SpD / 4 Spe
Bold Nature
- Scald
- Haze
- Recover
- Knock Off / Toxic 
Optional Move(s): 
- Gunk Shot
- Liquidation
- Toxic Spikes
Optional Item(s): 
- N/A 
Optional Ability: 
- N/A 
Optional EV/IV(s): 
- 248 HP / 8 Def / 252 SpD (Calm)
- 248 HP / 252 Def / 8 SpD (Bold) 
- 204 HP / 252 Atk / 52 Spe (Adamant)
Overview: With access to a fantastic ability in Regenerator and a good defensive typing, Mareanie excels at being one of the best defensive walls and pivots in the metagame. 
Mixed Defensive Pivot: Mareanie is a defensive wall, able to check the likes of Monferno, Combusken, Clefairy, Frogadier, Alolan Grimer, and Sliggoo. The investment in HP, Defense and Special Defense allows Mareanie to tank a +2 Firium and Fightinium Z from Monferno and Combusken regardless of the set. Mareanie also avoids being 2HKOed by Life Orb Frogadier’s Dark Pulse and tanks a +1 Adamant Fraxure’s Stomping Tantrum after Stealth Rock damage. Scald can 2HKO frail Fire-types such as Monferno and Combusken but is mainly used to fish for burns in order to cripple physical attackers. Thanks to Haze, it also acts as a reliable check against a good portion of the setup sweepers in the tier such as Monferno, Sliggoo, Combusken, and Pawniard. Recover allows Mareanie to recover health and stall out poisoned Pokemon. Knock Off allows Mareanie to remove Eviolite or other items from opposing Pokemon. Toxic badly poisons opposing Pokemon and lets it wear down both offensive Pokemon and walls like Servine, Prinplup, Staravia, and Togetic.
Checks and Counters: Bulky Grass-types such as Servine, Roselia, and Quilladin can easily switch into Mareanie. The former can start boosting with Leaf Storm, whilst the latter two can take advantage of its passiveness to set up Spikes. However, they do not appreciate switching into Knock Off. Machoke, especially bulkier Eviolite sets, can easily switch into Mareanie and threaten it with Knock Off and Earthquake. It also has the ability Guts to take advantage of Scald burns. Electric- and Psychic-types such as Electabuzz, Kadabra, Duosion, and Eelektrik can heavily pressure Mareanie with their super effective STAB attacks. Ground-type Pokemon such as Krokorok, Marshtomp, and Gabite hit Mareanie hard with Earthquake. However, they do not appreciate switching into Scald. Taunt users like Quilladin are a huge problem for Mareanie, preventing it from recovering and leaving it susceptible to setup sweepers, since it is very passive and cannot use Haze.
Optional EV/IV(s): An alternative spread of 204 HP / 252 Atk / 52 Spe with an Adamant nature is viable for the Gunk Shot, Liquidation, Knock Off, and Recover Mareanie set. It acts as a bulky Grass-type lure, capable of knocking out or heavily damaging common Mareanie switch-ins like Roselia, Servine, Quilladin, and Tangela with Knock Off into Gunk Shot. It also serves as a counter to Calm Mind Clefairy sets.