For weeks, Pokemon Go players have complained about bot users and GPS spoofers loading up local gyms with overpowered Dragonites and Snorlaxes. However, a recently discovered glitch might have found an even more infuriating glitch.
Some players have discovered they can insert Pokemon eggs into their local gyms. These eggs have no moves and have a CP of zero, but opposing players can't battle the eggs in order to clear them. That means that the eggs are in essence the ultimate gym defender, since they ensure that a team will hold the gym forever.
Don't worry, though, most players can't take advantage of the "egg defense" glitch. Players can only insert eggs into gyms by modifying Pokemon Go's API, so it's more of an illegal hack instead a normal bug. When Niantic discovers and fixes the bug (and now that it's making the news, we should see this fixed sooner as opposed to later), it's likely that the company will ban anyone who used it to "permanently" hold a gym as hacking Pokemon Go's API is very much against the Terms of Service.
For now, we can just add the "egg defense" bug to the list of things Niantic will have to clean up so that players can play Pokemon Go on an equal footing.