NFE Bulky Rocker + Rock Polish (Lairon) @ Eviolite  
Ability: Heavy Metal  
EVs: 252 Atk / 4 SpD / 252 Spe  
Adamant Nature  
- Rock Polish  
- Heavy Slam  
- Earthquake  
- Stealth Rock / Magnet Rise / Stone Edge

NFE Choice Band (Lairon) @ Choice Band  
Ability: Rock Head  
EVs: 4 HP / 252 Atk / 252 Spe  
Adamant Nature  
- Head Smash  
- Iron Head  
- Earthquake  
- Superpower
Optional Move(s): 
- Hone Claws
- Toxic
Optional Item(s): 
- Custap Berry
- Steelium Z
Optional Ability: 
- Sturdy
Optional EV/IV(s):  
- 252 Atk / 4 SpD / 252 Spe (Jolly)
Overview: Lairon is a reasonably good Stealth Rock user which can also function as a cleaner against frailer, offensive teams. Its typing and fantastic physical defense lets it switch into Pokemon such as Clefairy, Alolan Grimer, Staravia, Pawniard, and Vullaby well. Unfortunately, its poor special bulk, 4x weaknesses to common Fighting- and Ground-type attacks, and 2x weakness to Water-type attacks leave a lot to be desired. However, it still has the good niche of being an offensive, hard-hitting Stealth Rock user and setup cleaner.
Bulky Rocker + Rock Polish: Rock Polish lets Lairon boost its Speed, outspeeding the entire unboosted metagame after one boost, including notable threats such as Electabuzz, Frogadier, and Haunter. Heavy Slam, in conjunction with the Heavy Metal ability, has 120 base damage against most Pokemon in the tier, giving Lairon a spammable STAB move which hits Fairy-types such as Clefairy and Togetic for super effective damage and hits most neutral targets hard. Earthquake provides a solid coverage move which hits Electric-, Fire-, Poison-, and Steel-types such as Electabuzz, Mareanie, Metang, Pawniard, and Magmar hard. Stealth Rock provides the team with hazards. However, if another Pokemon has Stealth Rock, Lairon can run Magnet Rise, which lets it set up on and wall Pokemon such as Metang, non-Choice Scarf Gabite, Vibrava, and Fraxure at +2. It can also run Stone Edge, which gives it a Rock-type STAB attack to hit bulky Flying-types such as Staravia and bulky Water-types such as Prinplup and Wartortle harder.
Choice Band: The Choice Band Lairon set gives up most of its defensive utility in exchange for being a threatening wallbreaker. Choice Band Head Smash hits any neutral or super effective target hard and Rock Head ensures no recoil damage is taken. Iron Head provides a useful secondary STAB attack to hit Clefairy and Togetic hard. Superpower is primarily used to hit Ferroseed, a defensive wall which resists both of Lairon's STAB attacks.
Checks and Counters: Bulky Water-types such as Prinplup and Wartortle can usually tank a few hits from Rock Polish Lairon and threaten it with Scald. Monferno can usually revenge kill a slightly chipped Lairon with Mach Punch / Vacuum Wave. Faster Choice Scarf users like Electabuzz, Frogadier, Monferno, and Krokorok can revenge kill Lairon at +2. Bulky physical walls such as Ferroseed, Quilladin, and Tangela can shrug off non-banded hits from Lairon and wall it. Choice Band Lairon is harder to defensively check and switch into because it is very strong. However, it is easier to revenge kill due to its low speed and weakness to common offensive typings in the tier.