The next anti-meta gym defender?

Here's my opinion:

For starters, Dusknoirs HP is horrendous. Machamp could run through it without too much difficulty, despite the immunity. It would just take a bit more tapping. Mismagius works, and it even has Dazzling Gleam which will certainly surprise Machamps, Rayquazas and Tyranitars alike. Unfortunately, Metagross resists this move, which makes it a viable counter. (which is what we didn't want) Dark Pulse and Shadow Ball work great, but I would think Shadow Ball would come out on top as the reluctant people who didn't want to switch from MC would resist Dark Pulse. Drifblim is really niche and only works against certain Pokemon, so a generalist team could blow by it fairly easily. But it would really anger people who brought in only Machamp. It does have coverage against Dragons from Icy Wind, which is a cool bonus. (Unfortunately, Metagross resists this move, so yadda yadda yadda) There is one flaw in this design however. Say you had Blissey-Gardevoir-Chansey-Drifblim-Snorlax-Mismagius. Just have 3 Dark Ttars and 3 Machamp.

The Slowdudes wouldn't make any difference, as Ttars hit them for Super Effective damage anyway, as well as the fact that Water Pulse is the definiton of sh*t.

Of the three, Drifblim has the HP and additional flying type to block Machamp. Its bulk (HPxDEF) is only 74 different from Dusknoir, which is "only" Ghost, and is therefore the better choice.

Mismagius has an additional 17% ATK, but is also only Ghost and lacks 3000 bulk by that metric (roughly 9%). I would choose Drifblim, as it shares optimum generic DPS movesets with Mismagius, namely Hex/Shadow Ball, but they're both reasonably equivalent choices in my book.

The problem with ghosts (and also slow dudes) is that they will still get run over by shadow ball mewtwo.

Gyarados deserves a mention since he will resist steel and fighting, while only taking neutral damage from ghost/psychic. He can also have crunch, which will punish both mewtwo and metagross. The glaring weakness here is that Gyarados still has a 2x weakness to electric, but no pokemon can resist every type :)

What made Fairy such a potent defensive type was also walling dragons and Tyranitar. We may see an increase in Ghost-types on defence, but that would make Tyranitar a more popular gym attacker. Metagross with ZH/MM (as a defender) can handle both Machamp (some may be misled by the NVE message) and Tyranitar.

Defending doesn’t really matter anyway except Blissey and golden raz.

Metagross is weak to ground, dark, ghost, & fire. Ground(usually comes with rock typing) & dark are both weak to fighting which is bad because Blissey share the same weakness. Most ghost pokemon are glassy so thats out of the question. that leaves fire types as gym defender?

Charziard resist both steel & fighting. I figure I'll throw that in there

Well Metagross may destroy Togekiss when it's finally released, but at least Togekiss will wall Machamp and hit it with super effective damage. All in all it seems Blissey will still be queen but certainly mixing ghost and fairies will be more common than just Chansey/Snorlax/Slaking

Aside from the obvious “golden razz is the only good defender”, I think gyms might require some variation now.

1: Blissey - still top tier
2a: Drifblim - walls Machamp, specialist, weak to ghost
2b: Togekiss - walls Machamp, weak to steel/rock
2c: Gardevoir - walls Machamp, weak to steel
3: Chansey - second tier, great bulk
4: Any listed in #2
5: Snorlax - Great bulk
6a: Another listed in #2
Other contenders:
Crobat - Walls Machamp
Muk - Resists Machamp, weak stats
Hariyama - Resists Machamp, hits Metagross hard, bulky
Gyarados - Packs a punch, resists Fighting and Steel, very weak to electric
Milotic - same as Gyarados, but also can hit Dragons and Grass hard with dragon tail/blizzard
Slowdudes - Good typing, bulky, resists fighting
Metagross - can hit machamp with psychic moves, meteor mash wrecks, bulky and high attack

It’d be interesting to see more bulky fire types in gyms as an answer to attacking Metagross.

And of course, the God:
Shuckle - You don’t fuckle with Shuckle

There isn't much how to stop MM Metagross from overtaking gyms, I'm afraid. Magmortar could be a future annoyance when released.

Milotic won't be too horrible, and Surf is rather hard to dodge, but overall weak. I wish Houndoom was bulkier and Alolan Marowak stronger :(

Looking at the far future, in Gen5 we'll have Volcarona, which if given Fire Spin / Flame Charge, it could be something.

The only defense that matters is Blissey + golden razz... in short term. That is the only thing that works when actively defending a gym. Now obviously for people living in medium density areas and not having time to dedicate to defend a gym for 30min+, what matters is annoy attackers enough so they look away to a different gym to attack for a few hours.

The occasional Confusion/Fire Blast Slowking? Resists both fighting and steel, hits super effective with one of it's moves against Machamp and Metagross, but not Tyranitar or dragons...

Air Slash/Blast Burn Charizard could also be an option. Piece of cake for dragons though.

I guess the best answer is diversity... between the usual tanks.