NFE Physical Wallbreaker (Monferno) @ Firium Z / Fightinium Z  
Ability: Iron Fist  
EVs: 252 Atk / 4 Def / 252 Spe  
Jolly / Adamant Nature  
- Flare Blitz  
- Close Combat  
- Mach Punch  
- Swords Dance
NFE Special Wallbreaker (Monferno) @ Firium Z / Fightinium Z  
Ability: Blaze  
EVs: 4 Def / 252 SpA / 252 Spe  
Timid / Modest Nature  
IVs: 0 Atk  
- Fire Blast  
- Focus Blast  
- Vacuum Wave  
- Nasty Plot
NFE Choice Scarf Pivot (Monferno) @ Choice Scarf  
Ability: Blaze  
EVs: 252 Atk / 4 Def / 252 Spe  
Jolly Nature  
- Flare Blitz  
- Close Combat  
- U-turn  
- Gunk Shot  
Optional Move(s): 
- Slack Off
- Stealth Rock
- Thunder Punch
Optional Item(s): 
- Choice Band
- Electrium Z
- Eviolite
- Life Orb
Optional Ability: 
- N/A
Optional EV/IV(s): 
- 168 HP / 252 Def / 88 Spe (Impish)
Overview: With access to both Nasty Plot and Swords Dance, a great offensive Fire / Fighting typing, priority, and a decent Speed tier, Monferno distinguishes itself as one of the best wallbreakers in the metagame. It is also a good Choice Scarf user. 
Physical Wallbreaker: This wallbreaker set can set up on passive pokemon such as Clefairy or when it forces switches from Grass- and Steel-types like Roselia, Servine, Ferroseed, and Metang. This physical wallbreaker set hits specially defensive Pokemon such as Roselia, Servine, and Sliggoo harder than the special set. Flare Blitz is a strong STAB attack which hits Grass- and Steel-types such as Roselia, Servine, and Ferroseed very hard. Close Combat hits bulky Water- and Dragon-types such as Prinplup, Sliggoo, and Fraxure who resist Flare Blitz, as well as Dark- and Normal-types such as Pawniard, Krokorok, and Munchlax. Mach Punch acts as fantastic priority, capable of taking out faster weakened threats such as Electabuzz, Frogadier, and Choice Scarf Krokorok. Both Inferno Overdrive or All-Out Pummeling on both wallbreaker Monferno sets act as nukes at +2.
Special Wallbreaker: This special wallbreaker set can also set up on Clefairy and on forced switches. This set hits physically defensive Pokemon such as Gloom, Metang, Munchlax, Quilladin, and defensive Staravia harder than the physical set. 
Choice Scarf: Choice Scarf Monferno acts as good speed control; it is capable of forcing out or revenge-killing fast frail threats such as unboosted Electabuzz, Frogadier, Haunter, Kadabra, and Servine. U-turn chips and gains momentum on forced switches and complements any VoltTurn team well. Gunk Shot hits Fairy-types like Clefairy and Togetic for good damage.
Checks and Counters: Defensive Mareanie counters all Monferno sets barring the rare Electrium Z Thunder Punch set, since it resists both STAB attacks and threatens Monferno with Scald and Haze. Bulky Water-types such as Prinplup, Wartortle and Marshtomp are capable of tanking a +2 All-Out Pummeling if they are invested in the correct defense and hit Monferno hard with Scald or Earthquake. Gabite outspeeds both wallbreaker sets and can revenge kill it. Lampent is a hard counter to Monferno, since it is immune to both STAB attacks. Monferno is also frail, which means it can get OHKOed or heavily chipped if it attempts to set up and the opponent stays in. Offensively, Haunter can revenge kill wallbreaker Monferno sets with Sludge Wave, since it is faster and immune to Mach Punch and Vacuum Wave. Kadabra can also revenge kill wallbreaker Monferno sets. However, neither can switch into Monferno.
Optional EV/IV(s): An alternative set of 168 HP / 252 Def / 88 Spe with an Impish nature is viable for the Stealth Rock, Flare Blitz, Close Combat, and Slack Off set. This set acts as a good Stealth Rock setter and physical wall, capable of walling physical threats such as Alolan Grimer, Pawniard, Quilladin, and Klang. It can also tank a hit from Pokemon such as +2 physical Monferno, +2 Combusken, and +1 Fraxure and chip or revenge kill them if they are weakened.