everytime I try to battle the grass gym it says one or more of my pokemon exceed the level cap of the gym, but I do have pokemon above level 55 and even that won't work. I'm not really sure how the gyms work yet, but some help would be nice.
If you do pass the level cap, you can purchase Common Candy, which will decrease the level of a pokemon by "1." You can purchase then by running the command /lowerlevel. If you need anything else, feel free to let us know!