Niantic has announced on their website that the newest update for Pokemon GO will be making adjustments to how Gyms work; particularly when it comes to training at friendly occupied Gyms.
When the update goes live, you will be capable of bringing a full team of six Pokemon to battle instead of just one. In addition to this change, Niantic says that “the CP of the Pokemon you are training against may be temporarily adjusted lower.” With a weaker opposition and a total of six Pokemon at your side, being able to clear a Friendly Gym and level your precious Pokemon has never been easier. This means that even if you might have extraordinarily weak Pokemon with you in comparison to the ‘mons overseeing the Gym, you will still be able to help out.
So far there is no estimated release date for this update. With the ever continued promises of grand content additions to Pokemon GO, Niantic seems committed to support the game through regular content patches.