Hitmonlee should be C rank. Late game when your opponent only has a few offensive threats left/their walls are weakened significantly, Hitmonlee comes in, Normal Gem Fake Out's, and proceeds to sweep with Close Combat, Stone Edge, and Earthquake. After eliminating bulky ghosts, unless your opponent has their Crobat already out on the field with more than 25% HP, Hitmonlee is going to do some serious damage to their team. Of course, crippling flaws being it can't take on ghost types at all other than Chandelure, it doesn't have a guaranteed KO on Heracross unless you have SR on the field and you're running Blaze Kick over something, and it's frail as anything. Remains effective, however.
I'm also going to suggest Sceptile at least show up. It stops fighting types from switching in and will kill them if they try (Flying Gem Acrobatics says hi), and has the potential to break through some walls in the tier (Slowbro, all 4 possible spinners, Swampert, other various less notable stuff). Sceptile can be deadly if it gets an SD off or activates Unburden with Acrobatics, but it also has some major flaws, such as failing to do anything to Bronzong. Sceptile outspeeds everything unboosted in the game after Unburden (except something like scarfed Deo-S and scarfed Ninjask, because both are totally viable), and even most boosted things. As said, it doesn't like most walls that occupy UU, and works better as a killer of all things offensive. I'm suggesting B, as it effectively is a Crobat that possesses the ability to always kill bulky waters and also take out all of the spinners (ignoring the fact that Blastoise fits into both of these groups), which I think is a significant enough niche for it to fit in to. Partially outclassed? Check. Still very dangerous? Check.
Unburden users. Yay.