The gym in Dewford Town is run bun Brawly, a Fighting type master. He will be waiting in the gym which is a pitch-black maze.
find all the other trainers in the gym
Find cut
go to enterna city
i think the 2nd gym leader is in Jublife or Oreburgh city.
The second gym leader is brawley of Dewford town. You will come to the PetalburgGym second, but that's the last gym leader you'll battle.
The second gym is the Dewford Town Gym with Gym Leader Brawly.
The Second Leader Is In Eterna City
Find ALL the trainers beat them all, and then fight the Gym Leader at the front.
She is the gym leader in Shippo City. The gym is in the museum where u find N the second time.
walk in the gym
The Pokémon the second Gym Leader has in "Diamond" are Cherubi, Turtwig and Roserade.
The second gym is in Eterna City. The gym leader is Gardenia, who specializes in Grass-type Pokemon.