As the pool of pokemon gets larger; the tiers will change. There is only so much room in OU due to the tier calculations [Usually about 46]. People never thought Heracross would be UU, for example, or Cresselia, back in Gen 4.
Every tier will be an entirely different place. We have the fairy type; changed Base Stats; new moves; new move accessibility; moves changed; new mechanics like electric being immune to paralysis, and so on. It already looks certain that Latias will be UU at least; it almost was in Gen5 and got hit pretty hard.
This is uncharted territory. We're not even in position to talk about the OU metagame yet; let alone UU; RU or NU. For all we know Metagross could be manageable by something that ends up down there.
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On the main topic; an indirect nerf I feel that will hurt is Starmie.
- Hydro Pump lost 10BP
- Ice Beam lost 5BP
- Thunderbolt lost 5BP
- There is likly a very common user of Shadow Sneak in OU now; Ageislash; who switches in on Starmie with near-impunity. Oh; and he gets Pursuit too. Just to REALLY screw with Starmie. [This applies for the Lati twins too]
- Assault Vest exists now; so Starmie can't blow holes in attackers
- Starmie's niche is arguably contested by Protean Greninja; who; while he does not get Thunderbolt; gets STAB Ice Beam, and gets attacks such as Dark Pulse; and even U-Turn for momentum.
- Perma-rain is a thing of the past, so Starmie can't really run Thunder on a rain team and benifit from the extra x1.5 to Surf/Scald/Hydro Pump
Psychic types in general now feel notably worse.
1. Jirachi, Metagross, other steel/psychic can now be pursuit trapped and sucker punched.
2. With a viable Assault Vest user that gets Pursuit (Tyranitar), special attacking Psychic types can be switched into and killed a lot easier than before.
3. Many Dark types in general will likely see more use due to indirect buffs, even with the Fairy weakness. Such as the Assault Vest, Steel losing its resistance to Dark, Bisharp benefiting from Sticky Web, etc.
4. Ghost moves are more spammable than before, due to Steel losing its resistance, many things losing their Normal typing for Fairy (Togekiss), no one really uses Blissey/Chansey as much as they used to anymore, etc.
5. Sticky Web hurts many of the fast/frail/hard-hitting things like Alakazam much more than things that actually see more use in this metagame.
6. Fairy moves offer better coverage if you need something to kill Fighting types. They don't cover Poison, but Fairy/Ground offer reasonably good coverage together - much better than Psychic/anything.
7. With the rain nerf and new Pokemon/typing combinations, Celebi will probably see less use. Azumarill resists both Water and Fighting now and has far fewer weaknesses, isn't hurt by Pursuit/Uturn/the random Keldeo with HP Bug/Ice/Ghost, etc. Of course they have different uses from each other, but still...
As for Paraflinch, Electric types were never the best target for that strategy anyway, since they resist Iron Head and Air Slash. Magnezone resists both moves 4x. Even though it's slower than the only 2 Paraflinchers that see use (Jirachi and Togekiss), no one would have aimed to Paraflinch it before due to the 4x resist doing extremely low damage to it each turn/Magnezone's potential to kill it with a weakness once it finally didn't get haxed. There were far better things to do to Electric types, such as hitting them with any Ground move...