[@LuckyBlackCat][@OtomostheCrazy] I will go on and say that the gym leader's Pokemon will remain level 8 to keep things more balanced even after we get some training in. 

Gym leaders have access to things we simply don't. I mean, they are essentially the move tutors for their type.(it's also kind of something that the games' gym leaders do with their Pokemon too. Then again, they also evolve their Pokemon at levels they shouldn't be able to.)