Meta Analysis of Gym Defense [Outdated]

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People always say "if someone wants to take down a gym, they will". Which is generally true, but uninteresting... if you don't think about the first clause. It has been known since the early days of GO that the best defense is not being attacked. In the previous gym meta, 10-story-tall towers filled with Blissey and city-wide dominance prevented assault by breaking people's will to fight. In the new meta, gyms are limited to 6 slots with no duplicates—declawing Blissey’s influence—and with motivation decay, any defensive power a gym had is forfeit after a single assault (or a few hours).

What prevents gyms from being attacked in the current meta is the availability of weaker targets. Gyms that contain a relatively motivated Blissey and Snorlax, gyms with near-fully-motivated Pokemon, tall gyms that suggest power and motivation, and use of Pokemon that cover each other's weaknesses are all sources of deterrence that make trainers think twice about attacking gyms. Even the illusion of a raid boss “taking over” can steer players away.

This meta-analysis covers all of these strategies and attempts to synergize them to produce the ultimate gym defense. Not only will the strategy provided give you the best performance in terms of wasting your opponents' time and causing them to waste potions, but will also make the majority of players think twice about attacking your gym in the first place; be it for gold or glory.

For an audio version of this meta-analysis check out this video


Where Diamond and Pearl had the dreaded SkarmBliss combo, Pokemon GO has the beastly BlissLax duo. Even more hardcore players flinch away from these two Normal-type behemoths when scouting for gyms to take. Their combination of high base stats, massive HP (that’s doubled in gyms), sole weakness to Fighting, counter coverage to that one type, and potent, broad coverage, hard-to-dodge multi-bar charge moves make these two the definition of gym defense; all quiver before them.

Their Achilles's heel is their high base CP, significantly reducing their potency after four hours and making their existence nearly inconsequential after eight. That is, if they’re near max level.

The CP Decay Curve and Chansey

Pokemon above 2400 CP have their CP drop by 10% per hour. Once they have their CP drop by ~35%, it only takes two attacks on the gym to knock them out, and after ~70% it only takes one. This poses a problem for Blissey and Snorlax on long-term gym defense in that they’re only truly effective for roughly 4 hours. However, some Pokemon are resistant to the math.

Pokemon with CP below 2400 CP have their CP drop by the following rate:

CP_drop/hour = 4.975 * 1.001616 ^ (MaxCP)

This rate was first proposed by u/kk5566 in their analysis on motivation decay. Later, u/DrThod_PokemonGo did us the pleasure of making a graph representing this rate, along with his own data plots added to the graph.

u/Ryanoftheday (aka RyanSwag) later took this information and simplified it:

The data suggests that using defenders with 1600–2100 CP is most optimal for defending when aiming for up to 4 hours, and that using Pokemon with less than 1500 CP is most optimal for defending 8+ hours. While only using Blissey or Snorlax at a max of 1500 CP is fine, in RyanSwag’s analysis a 1500-CP-or-less Blissey underperforms significantly when compared to a 1000–1500 CP Chansey sitting in a gym. They may even underperform a 1000–1500 CP Steelix or Azumarill due to their bulk and handy resistances.

That being said, even without the CP-decay factor, Chansey is still one of the most optimal gym defenders. While she lags a little behind Snorlax, she is far above everything else by Pokebattler’s standard. Due to the CP-decay curve, Chansey surpasses a maxed Blissey in value after 4 hours, making it extremely valuable for gym defense. While unintentional on Niantic’s part, Chansey surpassing Blissey through game mechanics and utility parallels well with the console games. Above all else, Chansey’s power is a true testament to its evolutionary line.

Things look pretty up for Chansey, that is, until you consider gym height.

The Tall Gym Factor: Chansey’s Bane

When looking at gyms, you may notice this duality: some gyms are little pancakes where other gyms stand tall with banners hanging. u/eric654256 investigated this phenomenon and found that gym height is based on the sum of all defenders’ current CP. If the CP total exceeds 8000, the gym is noticeably tall. If the CP total is below 8000, then it’s small.

Since small gyms suggest the Pokemon are either weak or highly demotivated, and talls gyms suggest the defenders are more robust, logic would suggest other trainers are more likely to target small gyms opposed to tall ones. For players looking to maximize their time defending, aiming to maximize the length of time a gym remains tall is a priority. Since the CP-decay curve complicates this venture to an extent, u/eric654256 developed a formula and made a graph based on that formula to determine the amount of time it takes for a Pokemon to reach 1333 CP (8000 divided by 6)

This suggests that Pokemon above 2850 CP would be ideal for keeping a gym tall for the maximum amount of time. Considering Blissey and Snorlax’s max CPs exceed 3000, this is no biggie. Players aiming to have the best of both motivation decay and gym height may prefer being close to 1952 CP, which will keep gyms tall for ~5 hours while maintaining a “3 hits to KO” motivation range for ~5 hours. All of this poses a problem for our little friend Chansey, whose max CP is 1469.

While the inclusion of several 3325+ CP Pokemon balances out her negative impact on sum of CP’s to maintain gym height, each one included diminishes the advantage of having a lower motivation decay rate. This conundrum is eliminated when you factor in The King.

The Slaking Factor

Thanks to Slaking’s gargantuan 4548 max CP, its inclusion enables players to use lower CP Pokemon to maintain higher-for-longer motivation while also keeping the gym tall for the previous maximum length of time. This removes Chansey’s negative impact on the gym-height strat, giving trainers the best of both strats. More importantly, Slaking’s influence can enable trainers to participate in the gym-height strat without coordinating with other players.

Slakings above level 30 won’t hit 1333 CP until after nearly 7 hours. If aiming for the previous max 6 hours of tall, the goal CP would change from 1333 to 1236. If aiming for the previous reasonable max of 5 hours, the goal CP would be 1145. While this doesn’t sound like much, it does open the door for lower CP Pokemon. Depending on how close to max Chansey is, this inclusion of Slaking puts the influence of its diminishing CP on par with 2850–3325 CP Pokemon.

Whether you’re for or against Slaking as a gym defender based on its performance, its influence on these strategies cannot be denied. A Play Rough Slaking can really hurt some careless attackers. On partly-cloudy days, it could pay to be extra mindful of weather-boosted Slakoths in the area.

The Other 2 Gym Slots

Since BlissLax and ChansKing lock off 4 of the 6 slots in a gym, there are only 2 slots left to play around with. The “Elite 4”’s Normal-typing suggests you’ll want to cover their Fighting-type weakness, possibly with Fairy, Psychic, and Flying-type defenders. Their powerful Fairy-type charge moves may also bring in Fire-type attackers (who resist Fairy-type damage), which increase the value of Water, Dragon, and Rock-type defenders.

While you can use a Pokemon that only resists Fighting (like Gardevoir) or only resists Fire (like Milotic), here’s a list of notable Pokemon that can do both.

  • Dragonite - Excels in active gym defense and keeping the gym tall
  • Gyarados - Like Dragonite but with a few trade-offs
  • Slowdudes - Excellent for all gym-defense strategies
  • Azumarill - Great for long term gym defense
  • Tentacruel - Excellent for this one weird trick...

One thing all of these Pokemon have in common is they don’t like Raikou. Given Raikou’s potency as a neutral attacker also makes its inclusion non-problematic in the face of the Normal-types. With this in mind, Rhydon, Steelix, and Donphan may also help flesh out your defenses if Raikou is anticipated.

One Weird Trick..

Another way trainers can help deter attackers is by placing a ‘Raid Boss’ Pokemon in the 6th gym slot. While we don’t have any hard data to go off of, it can be assumed that all players have at one point dismissed a potential target because they thought a raid was going on. While it is a goofy strategy, only Blissey, Snorlax, and Chansey have a concrete influence on performance statistics. After those three, everything else is basically garnishing, so very little is lost by putting a ‘Raid Boss’ in the 6th slot to dupe less-attentive players.

For the best results, use either a tier 2 or 4 raid boss since players are far less interested in attacking them. Using Tyranitar may have the opposite effect since the grief of it not actually being a Tyranitar raid may incite an attack.


Using the strategies presented, gyms should be able to float that much longer in moderate-to-low–turnover locations. For most players, the presence of BlissLax is enough to make them pass up your gym. For others, the time consuming process of having to fight all six defenders three times or having to select multiple attackers and switch around is enough to make them seek out another target. A gym that stands tall while others are flat may cause them to not even look at it in the first place. And oddly enough, the presence of a ‘raid boss’ Pokemon on the top may dupe them into thinking it is a non-viable target to begin with.

If you have goals to maximize your time defending a few gyms or to get more gold badges, the combination of BlissLax and ChansKing will grant you an intimidating presence that may be enough to ward off both the frugal and the meek. As always, any defense is forfeit to someone who has the will, but the daily gym grind is already an arduous experience. As in the previous meta, the banality of the siege trumps all.