Klefki for A+
It can get a T-Wave on anything that is not immune and 25% of the time for free. It can also serve as the fairy type for any build meaning that there is little reason not to use it, and it's one of the few mons that can actually make good use of Spikes. It can also anti-lead many threats and has no trouble against Deo thanks to Foul Play. As if this wasn't good enough it can check any set up sweeper with T-Wave + Toxic and circumvents foe Substitute use thanks to Prankster.
Thunder Wave + Swagger + Substitute
Well, I think the main thing that holds Keys from being A+ is that 4th move slot. The problem is you want Toxic for Defoggers coming in on Spikes stacking, TWave for well everything, Spikes because Keys is best Spiker, but then there's that divide. You want Play Rough because you kinda get annoyed by Sub GeoXern when trying to break its Sub, but Foul Play is more useful in general, but you can't pressure Sub GeoXern, which is starting to become a thing. Also, no offense, but Klefki can't really stop opponents from getting up hazards, it only deters them, so I wouldn't truly classify it as an "antilead" unlike stuff like Thundurus, Sableye and Deoxys formes with Magic Coat. However, this thing is super useful and checks a crapton of things, and my only real gripe with it is it doesn't hit too hard considering I use mine all throughout the match, and I think it should still remain
A.
Moving to a different topic, Shuckle hasn't been ranked at all, and even though I've only seen Fireburn use it, I've grown fond of it as a Sticky Web setter. I'm going to set a broad preliminary ranking for
C+/B- because I have no idea wtf I'm talking about. First of all, unlike Smeargle
who is for total scrubs why is it ranked higher than Ray you silly peasants who can't take a hit and exists solely as a suicide lead, Shuckle is hella bulky, and therefore can set Sticky Web up more than once if you play it right. It also has SR with it (good package imo), can use Toxic to swat away Defoggers which are Web team's greatest annoyance, and has Encore for stuff that want to set up on it. It is also very bulky (Ik I mentioned that already) and with low HP, so Lefties isn't too necessary on it (It has Sturdy so no need for Sash), so it can run stuff like Mental Herb to at least get Web up against non-Magic Coat users or not-Smeargle/Darkrai
or even Quick Claw if you're tough enough. However, it is kinda set-up bait without Encore, and it is slow and weak as balls (5 base Speed #gottagofirst), and it doesn't have the movepool that Smeargle does, but I think
C+/B- is a nice place for it imo.