Sub Belly Drum (Magmar) @ Aguav Berry  
Ability: Vital Spirit  
EVs: 4 HP / 252 Atk / 252 Spe  
Jolly Nature 
- Belly Drum  
- Fire Punch  
- Thunder Punch / Dual Chop
- Substitute / Mach Punch / Dual Chop

Z Belly Drum (Magmar) @ Normalium Z  
Ability: Vital Spirit  
EVs: 252 Atk / 4 SpD / 252 Spe  
Jolly Nature / Adamant Nature
- Belly Drum  
- Fire Punch  
- Dual Chop / Mach Punch
- Thunder Punch / Dual Chop

All-out Attacker (Magmar) @ Life Orb  
Ability: Vital Spirit  
EVs: 252 SpA / 4 SpD / 252 Spe  
Timid Nature  
IVs: 0 Atk  
- Fire Blast  
- Psychic  
- Focus Blast  
- Hidden Power [Grass]  

Note: Magmar is the 5th fastest pokemon in NFE (Excluding the 3 LC pokemons that outspeeds as they're not viable). The Normalium Z Belly Drum set can set up twice, but is rather frail so struggles a bit too stay in for too long. Functions more as a wallbreaker 2 times, with Fire Punch as STAB, Thunder Punch for bulky Water types and Priority Mach Punch for faster mons that can threaten it out, like Scarf Krokorok. Dual Chop is good if you're anxious about Dragon types. The Sub set capitalises on either Stealth Rocks bringing Magmar into Aguav Berry range after a Belly Drum, or Sub doing that, being able to sweep with 75% hp left granting Magmar the opportunity to actually take hits. The All-out Attacker set capitalises on the popularity of the 2 previous sets, knocking down Marshtomps while other bulky Water types don't dare switching in fearing a +6 Thunder Punch. 

Checks & Counters: The Belly Drum sweeper can be checked by Marshtomp, and being outsped by Kadabra/Haunter without being able to do much damage back. The Special set is also walled by Bulky Water types such as Prinplup and Wartortle, but struggles less with Marshtomp. Dragons also don't care much about the special set. Chinchou is a hardcounter to both sets, and extremely physically bulky pokemons like Dusclops can also check both variants.

Other Options: A Choice Specs set with moves like Overheat could nuke quite a few common threats, but would still struggle with bulky Water types. Magmar also has a few cool support options, being able to run clear Smog, Will o Wisp and Toxic, and techs like Barrier and Counter can also be utilised.