I have a few issues with these tiers.
Conkeldurr needs to go up to B rank. Bulk Up with Guts is just too good. It is not eclipsed by anything above it. Don't bullshit me saying Toxicroak as Toxi requires more support than Conk.
It has problems dealing with super-effective and special neutral STAB attacks; Hurricane completely destroys him, Keldeo OHKOes with Hydro Pump even outside rain, and in fact, rain-boosted Water-type attacks make Conkeldurr cry. It's not going to survive any Psychic- or Flying-type attack. Also, too many fast things resist Mach Punch to it be useful against faster threats. Speaking of Mach Punch, Conkeldurr faces a lot of competition with Breloom, which has a more powerful Mach Punch due to Technician, a secondary Grass-type STAB, and acess to Spore.
Metagross - How in the Frick is Metagross so low? B rank. Metagross needs NO support to effectively run a Choice Band set in OU. Steel is ALWAYS a good type to have in OU.. Nothing switches into Meteor Mash / Zen Headbutt / Hammer Arm / Bullet Punch Choice Band set in OU. Don't bullshit me and tell me that is not viable in OU. Then tell me what in OU actually OHKOs Metagross? Don't worry I'll wait. Someone please enlighten me on Metagross' "flaws."
CB Metagross face harsh competition from CB Scizor, which has U-Turn and receives STAB from that too! So, it can easily escape from Magnezone. It also has a stronger Bullet Punch due to Technician. Also, most Ground- and Fire-type attacks will OHKO Metagross with no problems. If you don't have these two, don't worry, rain-boosted Water-attacks will do the job. In fact, Keldeo's Choice Specs-boosted Hydro Pump always OHKOes (even outside rain).
Vaporeon - I'd move Vaporeon to B rank as well. It's kind of a "slap on a rain team" with no negative consequences. It can hit hard, phaze, wall, you name it.
Its typing overlaps with Politoed, generally it's hard to run Vaporeon because it brings no new resistances at all, while compounding the Grass- and Electric-type weakness. If you use Vaporeon offensively, you have to use a defensive Politoed, while if you use Vaporeon as a supporter, you have to use a Choice Politoed.
Scizor - A Rank always. Swords Dance / Roost / BP / Superpower is timeless and needs absolutely no team support. It still revenges shit with Bullet Punch and with Roost and bulk it is a largely independent set that can exist on any team with no help. Hell, I would put it on an A-S borderline if there was one. Scizor isn't walled like half the shit on B rank is.. this is absolutely absurd.
Fire-type attacks easily end Scizor's life. A lot of would-be easy prey can defeat Scizor if they run a Fire-type attack. For example, a Tyranitar with Fire Blast can surprise Scizor. Don't worry if you cannot run a Fire-type move due to using a Rain team, for example; as Keldeo, a newly introduced threat, can OHKO Scizor with Hydro Pump even outside rain. In fact, Scizor hates Water-type attacks, even though it's not weak to them, and hates having to deal with Water-type Pokémon because they resist Bullet Punch. It's actually hard to sweep with Scizor because so many threats resist Bullet Punch, and very few are weak to them, so you need to weaken the opponent's team before sweeping. Scizor has much more opportunity cost than it had in the past. Also, currently it faces competition with Genesect, which has MUCH better coverage, but I think that Genesect will probably be banned anyway.
Sawsbuck - C tier. Sawsbuck is the best sun revenge killer in the game. Life Orb Double Edge revenges every non-resistant Offensive pokemon in the game.
Sawsbuck is very comparable to Stoutland, as both are Normal-types that have an ability that doubles their Speed under a certain weather condition. That said, Sawsbuck shares some problems with Stoutland. It can't revenge kill effectively outside sun, and Normal is a shitty STAB - at least it has a secondary Grass-type STAB to backup that. I generally prefer more consistent revenge killers, that while don't have the same speed as Sawsbuck on sun, at least doesn't lose their Speed outside that.