Also I wonder about Haxorus in S rank, with Mence and Hydreigon Haxorus is clearly outdone and overshadowed.
I nominate
Haxorus to drop down to
A/A+ rank.
I would prefer A rank, as even A+ is too much, Haxorus is insanely powerful, but it gets outsped easily, LO hydreigon outspeeds it, and Scarf Hydreigon outspeeds it even if it is +1. Florges, Slowbro, Escalivier, Krookodile, sometimes Chesnaught, and a handful of other pokemons counter it.
While the simplest pokemons can check it. But finding a check is relatively easy.
I would also nominate for
Klefki to drop down to
A rank.
I wonder why this thing is in S rank, SwagPlay is completely luck-dependent, and is not an argument for S rank, while Prankster screens seem amazing at first, combined with the mediocre defenses and average typing, it can be kill really easy, as UU is one of the biggest HO in the metagame, almost anything above average can 2HKO this thing through screens, T-wave support is nice in such a HO metagame, but not enough to justify S rank.
252 Atk Sheer Force Darmanitan Flare Blitz vs. 252 HP / 252+ Def Klefki through Reflect: 205-243 (64.4 - 76.4%) -- guaranteed 2HKO after Leftovers recovery
252 SpA Life Orb Hydreigon Fire Blast vs. 252 HP / 0 SpD Klefki through Light Screen: 170-201 (53.4 - 63.2%) -- guaranteed 2HKO after Leftovers recovery
252 SpA Chandelure Fire Blast vs. 252 HP / 0 SpD Klefki through Light Screen: 220-259 (69.1 - 81.4%) -- guaranteed 2HKO after Leftovers recovery
252 SpA Mega Houndoom Fire Blast vs. 252 HP / 0 SpD Klefki through Light Screen: 213-252 (66.9 - 79.2%) -- guaranteed 2HKO after Leftovers recovery
252 Atk Victini V-create vs. 252 HP / 252+ Def Klefki through Reflect: 187-222 (58.8 - 69.8%) -- guaranteed 2HKO after Leftovers recovery
252 SpA Life Orb Sheer Force Nidoking Earth Power vs. 252 HP / 0 SpD Klefki through Light Screen: 208-247 (65.4 - 77.6%) -- guaranteed 2HKO after Leftovers recovery
252+ Atk Choice Band Entei Sacred Fire vs. 252 HP / 252+ Def Klefki through Reflect: 189-223 (59.4 - 70.1%) -- guaranteed 2HKO after Leftovers recovery
252 SpA Moltres Fire Blast vs. 252 HP / 0 SpD Klefki through Light Screen: 196-232 (61.6 - 72.9%) -- guaranteed 2HKO after Leftovers recovery
While the 252/252+ Def Klefki does survive 2 hits from massive powerhouses from non-SE attacks such as Crawdaunt, it does end up set-up fodder to anything with priority (Ex. Crawdaunt doesn't mind getting screens up andgetting Paralyzed if it's gets up to +4 and spam Aqua Jet), immune to T-Wave, or doesn't mind T-Wave in the first place, to top that, Klefki has no means of recovery other than Rest or Sitrus Berry + Recycle, both which bring pressure on Klefki's movepool, as one of the best things Klefki has that I have yet to mention, is prankster Spikes.
Definitely not S rank.
Where did you even find hp fire...
I disagree that Analytic is a clearly better choice. In fact, Analytic and Magnet Pull aren't even comparble. Analytic is a wallbreaker that nothing can switch in. Magnet pull, however, is more a team supporter that helps Cloyster, Salamence and Haxorus to get pass their steel type checks like Klefi, Mega Aggron, Doublade etc while still pressurizes the troublesome things that it can trap like Slowbro with a powerful Volt Switch. I would not say that Analytic is a better choice when they fit different team's need.
I totally agree with other parts of your post though and Magnezone should be S Rank.
That's my bad, I assumed Magnet pull + HP Fire.
But now as I see your point, yes it does depend on the team, but it's just that Magnezone breaks a huge portion, if not all, the walls of UU. Though Magnet Pull does very good in weakning steel- types for Cloyster and Dragons in general to find space for a sweep. I do agree.