Not so possible to catch spoofer now. It is still possible at the 1st day launch in Malaysia. I've seen a guy occupying gyms around with his 2k+CP Dragonite and that is definitely a spoofer. Over the days, people might have catch up their progress since this game is on heat now.

Since last two updates, Niantic already prohibited the user to turn on Mock Location in Developer option. This is the option required to use for all fake GPS aps. Well some Android developer did come out some ROM that will hide the option and they call it Mock Mock Location, which is working now at the moment but I bet Niantic will get that over soon.

Anyway, what I can say is those people will not stay long with the game. The way they did it is not for fun, is more to commercial I guess, to sell the account.

Those who are spending on the game is slowly catching up to the spoofer's Pokemons. In another week, assuming the spoofers don't put a stronger Pokemon, we all could gang up & GB the gym continuously until the spoofer is kicked out.