>>15900611That would depend on the theme. You would get some really hard gyms or some really shitty gyms.
Personally I would like to see a gym leader that, rather than a set selection of pokemon, has a randomly generated pool of pokemon that are all similar in stats, but have different types. That would be a fun gym. It would force people to diversify a team and go in with the knowledge that they may not have all the counter-types they'll be facing.