Introduction

While Gens 3 and 4 have given us some new defenders such as Milotic and Togekiss, it has done nothing to change Blissey’s weight on the meta. Blissey aside, with motivation decay and Golden Razz berries, gym defense has become more about CP decay ranges and deterring attack altogether more than using a list of the best Pokemon (while also encouraging attack… eventually?). All that said, the curiosity is still there for who the best defenders are, despite how trivial gym defense has been.

Methodology

For the quantitative side of the model, simulations were used from Pokebattler.com using level 40 attackers against level 40 defenders, dodge specials pro, with realistic dodging. Rather than weighing the defender’s performance against its most optimized counters, they were pitted against the greatest gym attackers in the game. The rationale is that between battle parties and CP decay, it is unlikely and arguably unoptimal to shuffle attackers around based on each individual Pokemon in a gym and their moveset.

The primary attacking Pokemon considered are Machamp, Tyranitar, and Latios (who also represents Rayquaza and other Dragons). Performance against Raikou, Mewtwo, and Moltres are also factored in, but they were given less weight due to being legendary Pokemon. Additionally, rather than using the performance data for attackers in absolutely bad matchups (ex Dragonite vs Steelix), the most reasonable substitute was used with a weight against the attacker for having to switch in. The rationale is to give more credence to “switch-causing” Pokemon while keeping things in perspective.

From there, additional weights were assigned based on other qualities such as defensive typing and CP range. Given Blissey, Chansey, and Snorlax’s influence on the meta, weight was given in favor of Pokemon that resist Fighting-type damage and against Pokemon that are weak to it. Weights were also given toward Pokemon that do well for CP-decay strategies (good performance at 1000, 1500, and 1950 CP) and gym-height strategies (good performance at 1950 CP or max CP >3200).

In translating the quantitative model to the tier list, qualitative adjustments were made. Pokemon that were too similar to other defenders but notably worse were brought down (for example, Salamence has many of the same merits as Dragonite, but is limited to single-bar charged moves) and Pokemon that exploited aspects of the model despite not being that good were brought down (mostly Fairy-types).

Conclusions

The best defenders have more or less remained unchanged for the past 6 months. Gens 3 and 4 have brought in some new faces, but optimized gym defense can still be reduced to Blissey and Golden Razz. The most interesting additions are Milotic and Slaking, the former being the ideal Water-type gym defender in terms of bulk, typing, and coverage, the latter being extremely unique in its ability to KO counters or do nothing at all while sustaining gym height.