Gonna make a couple lower ranked noms since I think the C ranks are a bit too crowded atm.
C- > D/Unranked: Golem isn't a bad pokemon per se, but the reasons it's ranked where it is (Sucker Punch + Sturdy Custap) are so situational most of the time that it becomes extremely difficult to justify using it over stuff like Rhydon and Steelix which offer far more consistency.
C- > D: Tail Glow pass is cool and all, but it comes at the cost of sacrificing a valuable teamslot for something that has very few setup opportunities, and can be deadweight against offensive teams in most cases. Volbeat also has virtually 0 bulk, and it's typing offers nothing to most offensive teams (since you wont be using this on Stall or Balance.) Overall, it's just a tad too gimmicky for a spot in C-, and I think D would be much more accurate of a ranking for Volbeat.
C- > D/Unranked: Vullaby was a cute mon back when Sceptile was here, but nowadays it just gets pressured by so much, that I really dont see myself ever using this on a serious team. One of the main issues I have with Vullaby is that along with it's terrible matchup against every stealth rocker bar Mesprit, it has severe 4MSS, wanting to have Foul Play, U-Turn, Toxic, Roost, Brave Bird, and Taunt. It isn't completely useless though, being a decent check to Lilligant, Musharna, and Vivillon, but I dont really see these few decent matchups it has against a couple mons equivalent to a spot in C-.