Hey, it's me, Temporaryanonymous. Roomowner of the NEXT room on the main server of Pokemon Showdown. I thought I'd like to give some of my thoughts on generation six NEXT usage. I've been meaning to do this for a long time (starting when I wrote this tongue-in-cheek comparison of NEXT to gen 6:
http://pastebin.com/7isExXZM). However, instead of suggesting a bunch of changes and what should be done, I'm going to talk a little bit about how the actual gameplay features and meta of gen six will affect NEXT and what should be changed.
I am assuming Zarel will change the BST of only the few pokemon that GF did, and going to implement fairy typing and the steel nerf.
1. Weather is no longer permanent. Zarel got this one right, but I think there shouldn't be any perma-weather at all. I mean, Cryogonal with snow warning or phione with drizzle is fine, but when you have permanent weather and abilities like swift swim, sand rush, chlorophyll and the opponent doesn't have a counter weather, it gets pretty unbalanced. If anything, the meta seems more weather dependent.
2. Steel was nerfed. This is really one thing I'm looking at here, and that's Shadow Ball. Shadow ball was buffed to compensate for losing focus blast, but with gen 6, that's no longer needed. Gengar gets Dazzling gleam for decent coverage as a replacement to focus blast, and one of the last things the meta needs are Gengar and Aegislash hurling 90BP 30% spD dropping shadow balls that rip through everything not normal or dark type.
3. Crits have been changed. To accommodate, the autocrit moves should have their powers multiplied by 3/4 to get the new values (although nobody will really mind if a move like razor wind is now 60bp autocrit as nobody actually used it. Farfetch'd probably also would really appreciate a +3crit stick instead of a +2 crit stick.
4. Some moves have been changed. The three that are probably the most important are hidden power, technoblast, and knock off. Hidden power makes all non technician pokemon lack a bit more coverage, and it also slightly nerfs NEXT unown, which isn't that big of a deal. I remember saying back then, that Technoblast was too weak, even with 1.1 boost and STAB. Now it sits at 110 base power. If Gensect-Douse uses it, it'd be a 181 base power water move, possibly backed by download. This probably needs tweaking. Knock off is less of an immediate changer to NEXT, but a 97 base power dark move that removes items is very strong, and a lot of pokemon would benefit from this.
5. New moves. Some of them are quite disappointing, like parabolic charge (damage buff?) or land's wrath (let it hit flying/levitate or through protect?). Those are probably the only two that stand out and need buffing.
6. Gen 6 OU. As a whole, it seems very fast paced, and as some have called it, priority based. The top 3 gen 6 mons in OU are probably Aegislash, Greninja, and Talonflame. Greninja doesn't really get any new fun tools to play with, but Aegislash gets automatize. With a +3 boost to speed, neutral speed Aegislash is able to match base 128's, and an automatize weakness policy set is pretty popular. Talonflame is partially held in check with stealth rock, but NEXT stealth rock only does 25% to it, making it significantly stronger. As a whole, stealth rock and other hazards should also be reconsidered as defog allows an easy way to remove them.
I can probably think of more later, but this is all that's on my mind as of right now.