Ok I'm answering like everything so imma break it up so this makes more sense
Yes. Those are. Also Diancie and anything with Lum and Ho-oh. I'm not sure what this point is supposed to say. Darkrai has quite a few checks
This is a plus for Klefki. That's like saying "how does talonflame threaten serperior? It comes in, takes the Leaf Storm, and Serperior goes to Tyranitar on the Brave Bird anyway". That's the whole point of a check. Magnet Rise is useful on keys and lets it check EQ Arc/Megaray
This is a lot of theoretical stuff. Yes, Arceus can wear down keys, but even in this scenario you're forcing it out multiple times while your team has the opportunity to get stuff done. Maybe Arc can wear it down eventually, but it sounds like Klefki did its job. Plus the opposing side has to switch into foul play or Twave, not many mons want to take both, so it's not like keys cant be annoying. This is a totally regular scenario you're randomly calling poor for keys.
Double switch? Plus keys can fire off free Twave/Foul Play/Spikes as mentioned earlier
Keys isn't an amazing Ekiller check. However, how on earth are Darkrai and Megaray great checks when you have +2 Espeeds doing a shit ton to them? I mean lum Ekiller easily takes out non-FB Darkrai variants (I really havent seen much FB when it has so many things it wants to run already) and as for Megaray
+2 252 Atk Life Orb Arceus Extreme Speed vs. 0 HP / 4 Def Mega Rayquaza: 320-378 (91.1 - 107.6%) -- guaranteed OHKO after Stealth Rock
+2 252 Atk Arceus Extreme Speed vs. 0 HP / 4 Def Mega Rayquaza: 246-291 (70 - 82.9%) -- 62.5% chance to OHKO after Stealth Rock
Magnet Rise keys is the only one which can come in on +2 arc once it's gotten a kill and force it out. This is a specific and fairly irrelevant scenario, but point goes to keys
My issue with Darkrai to S is that it's really shaky. You have lum and magic bounce and magic coat flying around everywhere and plenty of good checks and bulky things. And while Darkrai is good, with this random status preparation flying around on every mon it can just lose effectiveness in some games. In addition, most of the things that you can use to patch up your darkrai weakness are easy top tier Pokemon that come with little opportunity cost like Xerneas or Ho-oh. I don't doubt that it's a top A+, but it really doesnt feel on the level of Xern or Arceus.
Now does that sound a lot like Klefki? Yes. In fact I really wouldnt be against a drop to A+ either. It can bullshit its way through entire teams but a lot of its checks are easy to slap on and it can often be stalled around by switching back and forth. Klefki is more of an S rank though because of how seriously it affects the meta. It's a huge defining force that's the main reason you're prepared for confusion and paralysis on everything, not darkrai. Support spiking sets are also seriously underrated, double team is bullshit too. And you cant just outrun keys like you can darkrai, unless you're in a really bad spot versus sub void darkrai you're likely going to be able to handle it with Mewtwo/MMX/Deo-A/MGengar/Scarfers/Skymin.
I hope this wasn't too stupid since I'm tired asf, don't particularly like my darkrai+keys paragraphs right now but ideally they get the message across.
Also
Zangooser pineco outclasses aron so at least replace aron with it. or rank probopass because they do the same thing. or do the reasonable thing and unrank aron. But Pineco is not getting fair treatment here. Also what happened to mega sableye rising? That was discussed and then never implemented or given a reason why it wasn't. Not to mention all the noms I'm quoting below, we had an active VR for once but council hasn't updated in like forever. The really important ones are the sableye rise and MEGAMENCE IN D RANK HELLO MEGARAY EXISTS