To be fair, Jolt isn't really completely eclipsed because of it's speed. But yeah you are probably right about C rank. C+ rank would be the most fitting rank after thinking about it a bit more.
Jolteon isn't getting a rank because it isn't getting an OU analysis.
Anyway I would like to propose
Kyurem-B to A (EDIT: A+) Rank. This thing is an absolute monster of a wallbreaker, and its great bulk allows it to take hits and dish out more against offense. Kyube is one dragon type who hasn't really lost much of anything with the introduction of the Fairy type, as most of its best sets do not involve the use of choice items or outrage, and it has plenty of powerful coverage options to deal with them.
With Teravolt Earth Power, he becomes a useful check to Rotom-W - switch in on Hydro Pump, Earth Power does 60-70 % while Rotom-W uses Will-o-Wisp. While Kyube doesn't appreciate burn, he can actually 2 or 3HKO non-defensive pokemon with dragon claw while burned, so he still isn't exactly easy to switch into, especially since he also has access to special STAB in Ice Beam.
Another big advantage of Teravolt is that Kyube is one of the few things that can hit Mega-Venusaur super effectively.
4 SpA Life Orb Teravolt Kyurem-B Ice Beam vs. 252 HP / 252+ SpD Mega Venusaur: 190-226 (52.1 - 62%) -- guaranteed 2HKO
EDIT also, max special attack Kyube can OHKO physically defensive Mega-Venusaur
That's pretty impressive considering the number of things that can 2HKO Mega Venusaur from full health (practically zero).
He's just in general a terror to switch into and bulky enough to take a lot of punishment. I looked at the definition of A rank, but it didn't have anything that really applied to wallbreakers - Kyube can't sweep or wall significant portions of the metagame, that's not his job - so I can't use that as evidence. Whatever the borderline for a wallbreaker to make A+ rank, I'm almost positive Kyube fulfills it.
EDIT 2 well I look like an idiot now. It's already A rank. For some reason I thought it was B. Since I made such a nice long post, you can consider it to be an argument for A+ instead.