Pokémon GO has had a problem since the very beginning. Its basic mechanics create an atmosphere where cheating is not only very beneficial, but is also pretty easy to pull off.
Just alter your GPS info and you’re essentially a Pokémon GO god, able to move wherever, whenever, allowing you to catch whatever you want. Niantic has fought this, implementing some basic cheat detection and prevention, but it seems like they’ve really stepped it up lately.
Reports are flooding in across the Pokémon GO cheat community that many of their tools are no longer working (note: some of these fixes are a part of Android updates as well). Along with this, Niantic has spoken out, saying that they are working on stopping cheating, which usually involves “GPS spoofing”. Spoofing is what I described earlier, with various tools allowing players to change their phone’s GPS info to move them anywhere in the world. Combine this with a bot which can play the game for you and you can become extremely powerful in the game.
This usually also combined with a scanner that would tell them where they wanted to be at any time. Scanners have been fought for a long time, and many have been taken offline over the last few months. Many in the community decried these efforts from Niantic, mostly because the in-game scanner was broken. A new Pokémon GO scanner was added to the game though, and while it’s nowhere close to ideal, it has calmed the desire for third party scanners from much of the community.
That left GPS spoofing as the final major cheating system that was bothering most players. Seeing massively overpowered Pokémon in gyms, sometimes ones that never spawn in the area, was usually a hint that a spoofer was about. Some players have spent time taking down gyms only to see them occupied by a spoofer, with no one nearby who could have actually been playing normally. Reporting these players seems to have helped, and hopefully Niantic has more anti-cheat systems coming soon for Pokémon GO.