NFE Physical Wallbreaker (Monferno) @ Firium Z / Fightinium Z  
Ability: Iron Fist  
EVs: 252 Atk / 4 Def / 252 Spe  
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  
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): 
- 252 Atk / 4 Def / 252 Spe (Jolly)
- 4 Def / 252 SpA / 252 Spe (Timid)
- 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. The 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 while Close Combat hits bulky Water- and Dragon-types such as Prinplup, Sliggoo and Fraxure who resist Flare Blitz. Mach Punch acts as fantastic priority, capable of taking out faster weakened threats such as Electabuzz, Frogadier and Choice Scarf Krokorok. Both Firium or Fightinium Z on both wallbreaker Monferno sets act as nukes at +2.
Special Wallbreaker: This 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 & 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/Haze. Bulky Water-types such as Prinplup, Wartortle and Marshtomp are capable of tanking a +2 Fightinium Z Close Combat/Focus Blast if they are invested in the correct defense and hit Monferno hard with Scald or Earthquake. Gabite outspeeds 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 weakened.