Watch out, travelers! Team GO Rocket are taking over PokéStops around the world using their enslaved Shadow Pokémon. You can help fight back by challenging a Team GO Rocket Grunt at one of their discolored PokéStops. As a reward for defeating three of the Grunt’s overpowered Shadow Pokémon in a PvP-style battle, you’ll receive 500 Stardust and one of the Shadow Pokémon left behind by the Grunt. Our curious Silph Researchers have been hitting the pavement for the last two weeks in order to tease apart the mechanics of this new feature. Researchers have collected data from 2,500 battles since the beginning of August. Let’s dive in and see what we’ve found!

Key Findings

There are 13 distinct Invasion Types, which can be uniquely identified using two pieces of information: the Grunt’s warning message and gender.

which can be uniquely identified using two pieces of information: the Grunt’s warning message and gender. Once the Invasion Type is determined, each of the three Pokémon slots are drawn independently from a set list of one to three Pokémon species.

For Invasion Types where all second-slot Pokémon are available as a reward, there is an 85% chance that the reward Pokémon the Grunt leaves behind will be the first Pokémon from their battle lineup, and a 15% chance it will be the second Pokémon.

Invasion Types

As many travelers have already noticed, the warning message before a Grunt battle hints at the Pokémon you will face. There are 13 different warning messages and 13 Invasion Types. Simple, right? However, there are a few shared phrases that make things a bit more complicated.

Firstly, two Invasion Types that we’ve named Snorlax and Kanto Starter Invasions both share the three non-type warning messages: “Winning is for winners!”, “Don’t bother – I’ve already won!”, and “Get ready to be defeated!”. Secondly, both the Water and Magikarp Invasion share the warning message – “These waters are treacherous!”.

This is where the Grunt’s gender provides additional information. Each Invasion Type is always led by the same gender of Grunt. Snorlax and Water Invasions will always be led by a Female Grunt, while Kanto Starter and Magikarp Invasions will always be led by a Male Grunt, making them immediately identifiable.

Battle Lineups

Once the Invasion Type is chosen, each battle slot is drawn independently from a predetermined list of potential Pokémon. Once the Invasion Type is accounted for, there is no correlation between the Pokémon in the three battle slots.¹

There have been three waves of changes to the options available in each lineup slot since the feature was first released. The graphic below shows the possible lineups currently available in the game.²

Shadow Pokémon Rewards

After the dust has settled and you have emerged victorious from your Team GO Rocket battle, you will be given the chance to capture one of the Shadow Pokémon you just defeated. This encounter can be either the first or second Pokémon that you battled, but not all second-slot Pokémon are currently available.

We have discovered that the availability of a second-slot reward Pokémon is determined by the Invasion Type, not by individual species. This finding is relevant for two Invasion Types: Ground and Flying. Some Pokémon available in the second slot of these Invasion Types cannot be received as a reward from any Invasion, while others can. While Scyther (Flying Invasion) and Raticate (Ground Invasion) may be fought in the second battle slot of these Invasions, you will never receive them as a reward. You may, however, receive them as rewards from Bug Invasions (Scyther) and Normal Invasions (Raticate).

Our intrepid researchers have determined that these Shadow Pokémon are currently available as rewards from Invasions:

Invasion Type Second slot possible? Reward(s) Snorlax No Kanto Starter Yes Water No Magikarp – Dragon No Fire Yes Flying No Poison Yes Bug No Grass Yes Ground No Normal Yes Psychic Yes

Our data indicate that you have around a 15% (95% confidence interval of 12.5 – 17.5 %) chance of encountering the second-slot Pokémon if it is available as a reward and an 85% chance of encountering the first-slot Pokémon. Note that not all Shadow Pokémon are equally likely to be encountered. This is because some Pokémon are only available in the first or second battle slot. Additionally, Pokémon are unevenly distributed within a battle slot. Silph Researchers are continuing to work on exactly what these distributions are!

Parting Words

Team GO Rocket PokéStop Invasions are an exciting new challenge for many travelers, requiring thoughtful counter selection to beat difficult Grunts. There are 170 unique lineups currently available, but by using the information presented in this article, you can narrow down the next Pokémon you will face to at most three species. We hope that this knowledge helps you design optimal battle parties for each Invasion Type, use fewer Potions and Revives, and ultimately catch more Shadow Pokémon.

See you on the road, travelers!

¹ A chi-squared test of independence was used to test for significant correlations between each battle slot pairing for all Invasion Types (28 individual tests). A Bonferroni correction was used to control the family-wise error rate, with an α value of 0.05. The p-value threshold to call a test significant was therefore 0.05/28 = 0.002. All tests gave a p-value greater than 0.02.

² Credits to Senior Researcher Mattah for the graphic.