Shadow Pokémon first invaded Pokémon GO in July 2019, but the origins of these creatures dates back to Nintendo’s GameCube era. Shadow Pokémon have a fittingly dark backstory tied to Pokémon’s villainous teams, and in Pokémon GO, it seems they’ve also got a secret power up their shadowy sleeves.

Last July, the Pokémon GO Team Rocket update added Team GO Rocket to the game. This mobile twist on the classic evil team has been involved in various live events since its introduction, stealing resources from PokéStops and battling players who challenge its members. To face off against players, Team GO Rocket uses Shadow Pokémon - red-eyed, evil-imbued versions of regular Pokémon. Surrounded by an eerie purple haze, these monsters make a strong first-impression, but there’s more to them than just a spooky countenance.

The concept of Shadow Pokémon was first explored in Pokémon’s GameCube-based spin-off RPGs, Pokémon Colosseum and Pokémon XD: Gale of Darkness. In both titles, an evil team called Cipher was on a quest to corrupt Pokémon by “shutting the door to their hearts,” blocking out all emotions so they could focus purely on battling for Cipher’s gain. This would also sometimes result in a state called Hyper Mode, when the unstable influence of the Shadow-making process would cause Shadow Pokémon’s emotions to spike out of control, increasing their critical hit chance. Additionally, as a side-effect of Shadow Pokémon’s lack of emotion, they were able to attack enemy trainers as well as Pokémon, ignoring the Pokémon universe’s usual rules in favor of ruthlessly doling out damage.

Pokémon GO’s Shadow Pokémon aren’t quite as brutal, being unable to attack enemy trainers. In fact, the process by which they’re created seems different than the GameCube games’, as well. Rather than being subdued by the Shadow-making process, Pokémon GO’s Shadow Pokémon have been boosted, made “stronger through unnatural means” by Team GO Rocket, according to an in-universe Niantic blog post. Ironically, Shadow Pokémon in GO are actually weaker than normal Pokémon, with lower CP and a lower chance of having favorable stats. That is, they were weaker, but only initially.

Datamined information suggests Shadow Pokémon were buffed in a recent update, gaining a 10% boost to their attacks. Previously, the Shadow Pokémon’s poor stats encouraged players to purify them back into regular Pokémon (a mechanic introduced in Colosseum and XD), granting a stat boost and other benefits. The introduction of a hidden attack buff has the potential to make Shadow Pokémon a powerful ally in competitive play, especially if players invest in increasing their CP to its maximum. Dataminers also found evidence of Shadow Pokémon eggs being added to the game at some point, so perhaps Niantic is planning make these dark creatures a more integral part of the GO experience.

Next: Pokemon Go!: How to Hatch Eggs Effectively

Pokémon GO released on July 6, 2016, for iOS and Android mobile devices.