Don’t count on doing anything useful when GPS spoofing.
Niantic’s Pokemon GO is a craze of sorts, if you hadn’t noticed, and obviously players will look at ways to cheat the current system and get ahead. In one such case, one can attempt GPS spoofing – or making the game think the player is located somewhere that isn’t their local area – since Pokemon GO utilizes GPS data as a core mechanic.
Unfortunately, it’s not going to yield any positive results. A Reddit user attempted GPS spoofing on a dummy account and noted that you can’t obtain items from Pokestops, can’t catch Pokemon, can’t battle or claim Gyms and on top of that, any Pokemon that you try to capture will run away regardless of their CP.
Granted, some players have been more careful with the spoofing, making the game think they’re still within realistic distances of their current location. If you’re trying to make the game think you’re in a completely different city though, you might want to just play it normally.