The Gym helps you boost a creature's attributes as you level them up. Should your creature already be a high level, it will not retroactively add the gym bonuses for you unless you use the costlier Re-Roll option.
Currently the only Gym available is Coachroach's within the 2nd area of Onyx City, which becomes available in Episode 3 onward.
Gym Passes are needed to train a creature. Please note that the number of Gym Passes needed for Re-Rolling will be multiplied by the level of the trainee.
Gym Passes are purchased at Dimmley's Dumpster for a modest coin cost.
Choose a training option, then select a creature. Helpful information will then be displayed below the selector. Then click "Start Training" when you are ready.
You cannot boost a particular creature's attributes at the gym in the following circumstances:
Rebirthed creatures will not lose the knowledge of their training regime if you own the Four Arms of Vishnu.