Gyms are an excellent source of EXP, especially in Fire Red Rocket Edition, where EXP and money are pretty scarce. That said, you can reach the credits screen without fighting a single Gym leader ...

Skarmory, Claydol, and Cradily are relatively weak attackers, while Aggron, Armaldo, and Metagross excel in both physical ...

as it is more or less a direct copy of Pokemon Red. We will mainly be focusing on the path of progression through the Gym ...