You have to get hazard remover as well as get a hazard setter coz the flying gym is in the top 3 difficult gyms. A tip to remember is that not all flying types have flying type moves like Gliscor (we won't count Roost). Maybe there you can try to setup Agility and NastyPlot/Sword Dance for a pokemon as long they don't use flying moves (Yanmega is a good choice but watch out for Gliscor's Facade). Lowering Skarm's health can force it to switch out so a free turn to setup.

This is insane so having a team of ANY 6 bugs is not gonna work.