I prefer to pair Serperior with Heatran, since unlike other fire types it resists all of Serperior Weaknesses(2 of which Heatran is immune) checking Talonflame,Scizor and Ferrothorn if you lack HP Fire, Clefable if they come after you kill something.So I've been testing today, and Serperior/MGyara/Fire type is actually really good. It utterly breaks stall teams like they are tissue paper. has some trouble with bulky / hyper offense depending on what fire type you use. Run Talonflame and you're weak to Heatran, run
DarmVictini and you're weak to priority. Easy problems to fix though considering you still have half a team left to use.
I am using Suicune with them for now, since it does well against Greninja's most common sets.