(Sweet, I can use color texts (I know I used it before but not outside of quotes)....not sure if that's allowed but might as well mention it somewhere.... ^^;)
I agree to this. The fact that Rotom-H has a decent STAB (makes Heat more of a hit and run pokemon compared to Wash), absorbs two statuses and can inflict statuses to the opponent makes Heat good but not as good as Wash IMO.
Heat has 3 more resistances (can resist Fairy and make steel 1/4 resistant, which is sorta big....depending on your team) but 1 more weaknesses compared to Wash and one of the weaknesses is 4x (negated by Levi but still pretty bad). Not sure what else to say about Heat....similar movesets compared to wash but replace Hydro Pump with Overheat. Kinda feel Heat should be around the B range if not the borderline between B+/A. ._.
He fills many of the same roles as his W counterpart, but that usually is why he does not get much use and why he is outclassed. The two both resist Talonflame, x4 resist Steel, both make great use of Levitate, and while Wash gets the less weakness typing, Heat gets the better over all typing with when factoring in all his additional resistances.
Sadly he will always be compared to Wash, and seeing how Wash is A+ rank, I believe B+ rank is highly suitable.