This is a selective overview of Pokemon that could add to the current gym meta, either offensively and/or defensively. Slaking is excluded from this analysis as an outlier that will hopefully be dealt with by Niantic.
Generation 3’s 3000CP Club: Metagross, Salamence, and Aggron
Metagross (Steel/Psychic): 160 HP, 257 Attack, 248 Defense – 3644CP
- Resistances .8x –Normal/Grass/Ice/Poison/Flying/Rock/Dragon/Steel/Fairy
- Resistances .64x – Psychic
- Weaknesses 1.25x – Fire/Ghost/Dark/Ground
Defender: Metagross has the CP to outrank Dragonite, and with the right IVs could place above low IV Tyranitar as well. Also notable is that Metagross does not have a double weakness, unlike Dragonite and Tyranitar, and boasts a number of useful resistances due to its Steel typing.
When Gen 3 drops, Metagross will be the only high ranking Gym defender to resist Dragon type moves. Further, Metagross resists all of Dragonite’s possible movesets (Steel Wing, Hurricane, and Hyper Beam are NVE against Metagross), and all of Blissey’s possible movesets as well (though powerful as an attacker, remains somewhat unpopular due to the time it takes Blissey to defeat enemies, which will be further exacerbated by Metagross’s resistances).
With a .64x double resistance to Psychic type moves, Metagross will also have favorable matchups against strong generalists like Alakazam, Espeon, and Exeggutor (Metagross also sports a .8x resistance to Grass moves). In addition to these resistances, Metagross has decent bulk, being tankier than Dragonite and Gyarados (though falls below Rhydon and Tyranitar).
Now despite the lack of a double weakness, Metagross still has plenty of vulnerabilities.
Let’s look at Dark types first. Houndoom is a hard counter, as all of its possible movesets will be Super Effective against Metagross, and Houndoom has resistances to all of Metagross’s STAB moves (which Houndoom desperately needs because it is very fragile).
Tyranitar with Bite/Crunch (or Fire Blast, Stone Edge is Not Very Effective against Metagross) is also a good counter, though this is not Tyranitar’s most efficient matchup because it could take Super Effective damage from STAB Steel type moves, and you can be sure that a Gyro Ball (a strong Steel move already in the game) Metagross will hit very hard.
Metagross is weak to Ground type, but strong Ground types like Rhydon and Golem are also Rock, so they will take SE damage from Steel type moves just like Tyranitar. Donphan doesn’t have this problem, however neither of its quick moves benefit from STAB, and Tackle will be NVE here (Counter is neutral to Steel/Psychic). To be effective in this matchup, Donphan will need to have Earthquake, as Play Rough and Heavy Slam do not benefit from STAB, and are Not Very Effective against Metagross.
Ghost type is not a significant weakness as Gengar is very frail and takes SE damage from Psychic attacks. We don’t know what Metagross’s movepool is yet, but if it learns Confusion that will be absolutely devastating to an attacking Gengar.
Fire types (which Houndoom is as well) are not in danger of taking SE damage from Metagross’s STAB moves, and have a resistance to Steel type damage. Metagross, as a high ranking defender, will make Fire types more relevant in the meta.
I think this is a good thing, because there are many powerful Fire types (Fire Spin/Overheat Flareon comes close to Dragon Tail/Outrage Dragonite in terms of DPS) that unfortunately have not had particularly useful matchups thus far. If you use a Fire type that isn’t Houndoom, you will take neutral damage from Psychic types moves. Thus, in exchange for doing more damage with Flareon or Charizard, you won’t benefit from a Psychic-resistance.
Attacker: As an Attacker, Metagross will be a very strong generalist. Psychic type moves are only resisted by Tyranitar, and of course another Metagross. Of the common defenders, Vaporeon and Gyarados (and another Metagross) resist Steel type moves.
Metagross with two Psychic type moves comfortably attacks in Vaporeon, Gyarados, Dragonite, Snorlax, and Blissey (also recall that Metagross resists all of Blissey’s movesets) for neutral damage. Ground type moves are Super Effective against Metagross, so I wouldn’t use him against Rhydon unless you have two Steel type moves (even then, why take SE damage when you don’t have to).
Metagross is a clear upgrade to Pokemon like Alakazam (Psychic) and Scizor (Bug/Steel), because it is far more durable (sturdier than Dragonite or Gyarados). While it doesn’t have Alakazam’s attacking power, Metagross lasts longer due to its superior bulk and 9 resistances. In the end it will depend on movepool, but regardless I’d expect Metagross to be near the top of any attacking tier list.
Salamence (Dragon/Flying): 190 HP, 277 Attack, 168 Defense = 3532CP
- Resistances .8x – Water/Fire/Bug/Ground/Fighting
- Resistances .64x – Grass
- Weaknesses 1.25x – Fairy/Rock/Dragon
- Weaknesses 1.56x – Ice
I’m going to keep this one very short. In Pokemon Go, Salamence is basically another Dragonite. It is 13% less durable than Dragonite, but has a 5% increase in its attack stat. Salamence will deal more damage with the same moveset, but can’t take as many hits as Dragonite in battle. Due to its lower CP, Salamence will place below Dragonite (3581CP) in gyms.
Aggron (Steel/Rock): 140 HP, 198 Att, 314 Defense – 3004CP
- Resistances .8x – Ice/Rock/Dragon/Fairy/Psychic/Bug
- Resistances .64x – Normal/Flying/Poison
- Weaknesses 1.25x – Water
- Weaknesses 1.56x – Ground/Fighting
Defender: I’ll try to keep this part short as well. Aggron has a very high defense stat, and overall its bulk is comparable to Rhydon and Tyranitar. But it has two double weaknesses, to Ground and Fighting, as well as a weakness to Water (Vaporeon will be SE against Aggron while resisting Steel type damage).
Its vulnerabilities, in conjunction with a max CP below Vaporeon (3157CP), make it a bad choice for Gym defense. Which is a shame, because Iron Tail/Heavy Slam Aggron would have a very good damage output, and at least give it some coverage against Rhydon and Golem.
On offense, I think Aggron will shine. For starters, Aggron, much like Metagross, resists all of Dragonite’s movesets. Not only that, but Aggron has a double resistance to both Normal (Dragonite’s Hyper Beam) and Flying (Dragonite’s Hurricane) type attacks. Aggron would make a very tanky attacker into Snorlax, Dragonite, Salamence, and Tyranitar (Aggron resists Stone Edge, and is Super Effective with Steel moves).
While Ice types will take out Dragon types like Dragonite and Salamance faster, they will also take more damage than Steel types like Metagross and Aggron. Further, Aggron has excellent potential as a generalist against many of the Legendary Pokemon.
All Legendary Flying types are weak to Rock moves, and Pokemon like Moltres, Articuno, and Ho-Oh have a double weakness. Aggron has the added benefit of a resistance to Psychic type moves from Mewtwo and Lugia (Although Aggron needs to watch out for Focus Blast Mewtwo and Hydro Pump Lugia).
Noteworthy Mentions: Milotic, Gardevoir, Hariyama, Blaziken, and Walrein.
Milotic (Water): 190 HP, 192 Attack, 242 Defense – 2967CP
- Resistances .8x – Fire/Steel
- Weaknesses 1.25x – Grass/Electric
Milotic is one of my favorite designs from Generation 3. Unfortunately, in Pokemon Go it will basically be another Vaporeon. Vaporeon is a little tankier, has a slightly higher attack stat, and a higher max CP; Vaporeon will outperform it on offense and outrank it in gyms.
Milotic’s only advantage is it will be more potion efficient, since it has a much higher defense stat than Vaporeon. But unless it gets some kind of distinguishing moveset (new Water moves added with Gen 3 that are stronger than Water Gun/Hydro Pump), you can expect Milotic to be function as a slightly worse Vaporeon.
Gardevoir (Psychic/Fairy): 136 HP, 237 Attack, 220 Defense – 2964CP
- Resistances .8x – Dragon/Psychic
- Resistances .64x – Fighting
- Weaknesses 1.25x – Ghost/Poison/Steel
Gardevoir’s CP is too low to realistically be a defender, so I’ll focus on it as an attacker. An important point: if the base stat formulas do not change, Gardevoir will have the highest attack stat of all non-Legendary Fairy types in any generation.
Gardevoir, depending on its moveset, has the potential to either be a standout attacker, or a huge let down. Bulkier than Arcanine, and with the attack stat of Gyarados, Gardevoir has the makings of a really good generalist. Fairy type is Super Effective against Dragon types, and neutral to most of the common defenders (Vaporeon, Blissey, Gyarados, Rhydon, Snorlax) while only being Not Very Effective against newcomer Metagross.
What Gardevoir needs, and what the meta (in my opinion) needs, is a Fairy type quick move. If Gardevoir only learns Psychic type quick moves, it will just be another strong Psychic type attacker like Alakazam, Exeggutor, and Espeon. Currently, there are no Fairy quick moves; but, if Gen 3 were to release with a new Fairy quick move in Gardevoir’s movepool, that would be significant.
Fairy type is Super Effective against Dragon and Dark type, which both happen to be highly relevant in the current meta. And unlike Ice type, Fairy type resists Dragon. Completely Super Effective against Dragonite, Tyranitar, and Salamence (when it arrives alongside Gardevoir); no other Pokemon can do that right now because Clefable, Wigglytuff, and Granbull don’t learn Fairy type quick moves.
Gardevoir has the potential to become more useful with time, because many future generations will introduce high CP Dragon types (and there are plenty of them that will not have a double weakness to Ice).
Hariyama (Fighting) and Blaziken (Fire/Fighting):
Fighting type is an important commodity in the meta given the dominance of Blissey and Snorlax in gyms. Thus, I will discuss Gen 3’s best Fighting types together.
Hariyama: 288 HP, 209 Attack, 114 Defense – 2765CP
- Resistances .8x – Dark/Rock/Bug
- Weaknesses 1.25x – Psychic/Flying/Fairy
Hariyama is a bulkier Fighting type than Heracross, Machamp, Hitmonchan, and Hitmonlee (listed in order of decreasing durability). Despite that extremely low, potion-inefficient 114 Defense stat, Hariyama compensates with a higher base HP stat than that of Vaporeon and Lapras.
Haryiama will be almost as resilient as Poliwrath, and packs a significantly more powerful punch, with a respectable 209 Attack stat. It should make due with Rock Smash/Brick Break, but if it gets Counter/Dynamic Punch or Close Combat in its movepool, expect Hariyama to perform as a solid counter to Snorlax and Blissey.
Blaziken: 160 HP, 240 Attack, 141 Defense – 2631CP
- Resistances .8x – Fire/Grass/Ice/Dark/Steel
- Resistances .64x – Bug
- Weaknesses 1.25x – Psychic/Water/Ground/Flying
Blaziken will have a higher attack stat than any Fighting type currently in the game when Generation 3 arrives (aside from Breloom which has a 241 Attack stat, but is extremely glassy and is not on this list). While that sounds impressive, its drawback is its low durability. Blaziken is very frail, comparable to Hitmonlee and Hitmonchan (for further reference, they are both about as glassy as Alakazam).
To be even remotely viable against Blissey, it absolutely must have the best Fighting moves (Counter/Dynamic Punch or Close Combat). But even then, Blaziken will likely require close to perfect dodging and efficient move-use to be a match for Blissey. Depending on moveset, it might be borderline impossible for Blaziken to defeat a Zen Headbutt/Dazzling Gleam Blissey (of the same level).
Theoretically Hitmonlee and Hitmonchan (with their best movesets) can defeat a Blissey on their level, but in reality, winning is unlikely. While Blaziken might be a disappointment in terms of performance against Blissey, at the very least it should be a viable Snorlax counter.
Walrein (Ice/Water): 220 HP, 182 Attack, 176 Defense – 2606CP
- Resistances .8x – Water
- Resistances .64x – Ice
- Weaknesses 1.25x – Electric/Grass/Fighting/Rock
Walrein is very similar to Lapras, with a little less bulk but a higher attack stat. Walrein is notable because it is an Ice type comparable to Lapras that you can actually evolve to acquire. This is significant, because the best counter to Dragonite is still very rare, and hard to get candies for; and even worse, since Gen 2 was released Lapras now learns Water type moves (a Lapras with Water Gun and/or Hydro Pump is basically a worse Vaporeon).
Unless Niantic decides to make Spheal as rare as Mareep for some reason, you shouldn’t have trouble getting your hands on Walrein (a standard 3-stage 125 candy evolution). Assuming it learns Ice moves, Walrein will be an excellent counter to Dragonite and Salamence.
Jynx, Dragonite, and Cloyster all deal more damage to Dragon types, but Jynx is very glassy, Cloyster while adequate on bulk and DPS is outclassed by Lapras’s (and subsequently Walrein’s) longevity, and Dragonite still runs the danger of taking massive amounts of Super Effective damage from a defending Dragonite.