Your Eevee has a weird set. Focus fully physical or special, as its stats are pretty average, and you can/should only invest into one. IMO, Special is better, as Foul Play uses your opp’s attack, and everything except Leafeon is special. Scizor or Excadrill>Lucario, but Lucario is still ok. Swampert is fine, though I personally prefer Gyarados. The best Rotom form is generally Wash or Heat, though Heat is weak to Stealth Rocks.
The best offensive Fire mons are Chandelure, D. Chandelure(Oran Berry required), D. Emolga(after badge 7, in Roggan Town PC), M. Typhlosion(needs HP Grass), Blaziken, Volcarona, M. D. Froslass, Rotom-H, Infernape, D. Lilligant, M. D. Sunflora, Delphox, and Talonflame.
As for defensive options, you have Arcanine and D. Vespiquen.
For your team, assuming R-Wash, Swampert, M. Eevee, and Lucario, I would run Talonflame(with Gale Wings), Rotom-H over Rotom-W, D. Chandelure, Volcarona, or Chandelure.