GPS spoofing refers to changing a mobile device’s GPS location by using special GPS app without having to physically go to the new location. It has been widely used by Pokémon GO players yet Niantic has not done enough to prevent GPS spoofing.
Besides the ability to fake device’s GPS location, some GPS spoofing apps also provide a “joystick” feature that enables Pokémon GO players to “walk” to virtually any location on earth without having to move their lazy butt, so they can “go” to any PokéStop to collect items, or “go” to a PokéGym to battle while sitting in a couch. Thanks to GPS spoofing and Niantic’s lack of action, spoofers can easily control PokéGym and level up their trainers at a fast pace. If you play Pokémon GO, you can easily spot those cheaters: they have incredibly high-level Pokémon, for example 3K+ Blissey, 3K+ Dragonite. These Pokémon are very rare to get (usually by hatching 10K eggs) and even if you are lucky enough to get one, you will need to walk hundreds of miles to earn enough candy to evolve and level up to 3K, but with GPS spoofing, it is easy. Let me explain why. Some GPS spoofing app allows player to create a route between a source location and destination location, and once the route is started, the trainer in Pokémon GO will start walking by itself along the route, earning candy while hatching egg. So you can just put your phone on the table to let it play by itself while you are doing other stuff, and collect hatched Pokémon once a while and then put another egg in the incubator. If you do this around the clock, then your trainer can “walk” hundreds of miles easily without you doing much.
I believe Niantic knows the existence of the GPS spoofing issue, but so far they have not implemented any effective way to stop GPS spoofing, and it frustrated many players including me. With so many cheaters controlling various Pokémon Gyms, legit players have two options: 1. ignore them and play as usual; or 2. become one of them. I think I might choose the second option.