Nice to see the lower ranks cleared up a bit. I was gonna make some arguments about Hydreigon and Rotom-H moving up, but I'll think I'll hold off until the suspect test ends, since countering/checking Aegislash is one of the reasons you'd use them.
Well since you are all so adamant about discussing Mantine I'm going to try and derail all that by pitching my support for
Rotom-H to B-.
Rotom-H is a bit of an odd egg, and last gen was completely outclassed by its cleaning cousin, the washing machine. However Gen 6 has been very kind to Rotom-H, removing the ubiquitous rain, giving it a new, important resistance and making it easier to clear rocks.
Considering how close they are in role and performance, it's strange that their ranks are so far apart. I believe Rotom-H's current C+ ranking is because of this part of C ranking's definition:
Pokemon from this rank tend to face a lot of competition with the more commonly used Pokemon.
Rotom-W currently sits in A, and only differentiated to Rotom-H through its typing and stab move. So this will basically be a comparison between the two. Hopefully I can show that Rotom-H is not completely outclassed by Rotom-W, and is a better choice for a team in many cases.
I'll start with a list of Pokemon that each can handle better than the other (Down to A- rank).
Rotom-W:
Tyranitar, Landorus's, Azumarill, Greninja, M-Gyara, M-Ttar, Keldeo, Heatran, Hippowdon, Terrakion, Diggersby, Gliscor.
Rotom-H:
Thundurus, Aegislash, Mawile, Bisharp, M-Pinsir, M-Scizor, Talonflame, M-Venu, Char-Y, Ferro, Gengar, Breloom, Kyu-B, Mamoswine, Skarm.
Rotom-H handles just as many things as Rotom-W, they are just different. For covering threats on a team, Rotom-H is often a more suitable choice than Rotom-W. Rotom-H's Overheat has better accuracy and power, but isn't spammable. It's still more than enough in most cases, and scores a lot of neutral 2HKO's. It also misses half as much as Hydro Pump.
Rotom-H only has 2 real disadvantages against Rotom-W: A weakness to water, and to stealth rock. Depending on your set, it's weakness to water isn't very important since with a Scarf you can EV to voltswitch out before taking a hit. This means you can still handle water pokes such as Greninja, Keldeo and Gyarados well. I don't have much to say about the SR weakness except defog is your friend on either side, and nearly every team has hazard support.
TLDR - Why Rotom-H should be B-
- Similar to Rotom-W, an A-rank mon.
- However, not outclassed by Rotom-W because:
- Handles different threats to Rotom-W (just as many, though)
- Key Resistances to Fairy and Electric
Happy reading people.