Another major issue to the current gym system is that there’s only a few viable gym defenders. Every gym contains some combination of Dragonite, Gyarados, Vaporeon, Blissey, and Rhydon. The only variation occurs at the bottom of the gym, with Pokemon that quickly get knocked out when a gym comes under attack.
When dataminers first discovered changes to Pokemon Go‘s code in May, they found a line about limits to one Pokemon species related to gyms. If implemented, this could make a lot more Pokemon viable in gym play, either as second tier defenders or as new attackers. Only dealing with one Blissey or Dragonite per gym would also alleviate some of the frustration of not being able to make a dent in an enemy gym because you don’t have an effective Fighting or Ice-Type Pokemon.