You definitely can, and no proper trainer will look down on you for it. Though if you have mainly grass pokemon, you'll probably have a lot of trouble with Bugsy as well. He uses bug type pokemon, and those resist grass just like flying type pokemon do.
[Poor Izuku. Two gyms in a row that were just Bad News for grass pokemon.]
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[Poor Izuku. Two gyms in a row that were just Bad News for grass pokemon.]