Shield Dust should go up - Shield Dust is a great ability. Crunch and friends will never lower your defense, Dark Pulse and Headbutt will never flinch you, random fire, ice, poison, or electric moves will never burn, freeze, poison, or paralyze you, Earth Power, Flash Cannon, Psychic, Shadow Ball, and Focus Blast among others will never lower your special defense, Hurricane will never confuse you, Scald and Lava Plume will never hax you, Signal Beam will never confuse you, etc. Any move with an effect that has a percentage chance (even 100%) of happening will never happen.
Let's look at what I think are the most important uses of the ability: Jirachi has no way to hax you. Machamp (DynamicPunch) and Tornadus (Hurricane) can't either. Volcarona won't get any more powerful no matter how many times it Fiery Dances against you and Magnezone won't be able to boost up if you have it and you're a steel (Ferrothorn would love that, perhaps more than iron barbs). Nothing can flinch you with Fake Out, or boost its speed with Flame Charge, and you are completely immune to sets dependent on burns from Lava Plume or Scald. It's a great ability that happens to just be given to things that are really shitty. Look at the onsite description: "This is actually a really good ability, but you cannot expect to see it very much when the 5 Pokemon that have it are Caterpie, Weedle, Venomoth, Wurmple, and Dustox. Venomoth is somewhat usable nowadays but would always much prefer Tinted Lens to Shield Dust. The other 4 are just awful, and this is a shame, because this ability could be really good on the right Pokemon." Something like that sounds perfect for at least B Tier in my book.
Normalize should go down - I don't really think it takes that much discussion to show Normalize is a really shitty ability with little benefit coupled with a lot of drawbacks. Unless you're normal type, none of your moves have STAB, and, even if you are, you have no coverage and absolutely nothing to hit ghosts with. I can think of two uses for it, namely a ghost skill swapping it onto something else and being immune to their moveset or hitting things with status conditions moves they are immune to like Thunder Waving ground types or Sporing Sap Sippers (though poison still wouldn't work I believe). So we have an ability that is largely bad with a few possible uncommon beneficial uses. D Tier at best in my book.
Snow Cloak should be in B - Sand Veil is and they're the exact same ability just for different weathers. The fact hail is less useful/used than sand didn't keep Snow Warning out of S Tier, and it shouldn't keep Snow Cloak out of B.
Things I don't want to nominate yet but think we should consider:
I was also going to nominate Hustle, but if people think a discussion before doing that would be beneficial, I'll hold back on that. Hustle boosts one of your offensive stats with a draw back that, unlike Solar Power (an ability that consensus decided was B Tier) is able to be worked around (see Hone Claws Durant), and with a power boost that, unlike either Solar Power or Guts (an A Tier ability), doesn't require a set condition to activate. Unlike Solar Power, it also isn't a detriment to Special Attackers or Support mons (who take damage in the sun even if they aren't using special attacks with the former), since there is no accuracy drop for special attacks. The accuracy drop is bad enough to keep it out of A, but C tier abilities are supposed to "oftentimes not even [be] game changing." Whether it helps you with it's power boost or haxes you with the accuracy drop, that's never something that's going to describe Hustle.
I'd also want to consider whether we should nominate Klutz to move down to D as well. Like normalize it's a pretty shitty ability with pretty much two niche uses, namely tricking bad items onto things unexpectedly and being essentially immune to bad item trickers (Fling also used to be a niche, but that doesn't work in Gen V). Otherwise, it's just bad. No lefties, no life orb, no choice, no nothing. That's sounding pretty D in my book.
Also, similarly to my Snow Cloak nom, if we're nomming Rain Dish, I think we should consider nomming Ice Body since it does the same thing in hail and allows for some pretty obnoxious sets like Stallrein (and Regice once it's released).
Effect Spore, Poison Point, and Poison Touch probably deserve at least some discussion as well since we have Flame Body and Static up in B already, the first probably more than the latter two, but I can see a case being made for all of them. Cursed Body has a similar effect, so it might merit discussion as well.
Immunity too, since toxic isn't exactly uncommon, and it's the only way for something grounded that isn't steel or poison typed to avoid Toxic Spikes without an A Tier Ability outside of sunlight. The other status immunity abilities I'd consider for consistency's sake, but I feel less strongly about them.
Also, I'm sorry for being nitpicky and this isn't really a big deal but Iron Fist is spelled Iron Fists and for some reason that's been bugging me.