If you use a type advantage on a gym leader pokemon, you may be able to defeat the Gym pokemon at a lower level than stated. If you do not use type advantage, you might have to level up the pokemon more than the average.
Pokemon: Onix (Rock,Ground)
Onix is beatable around levels 14+, depending wether or not you use type advantage.
Pokemon: Pidgeotto (flying, normal)
Pidgeotto is beatable around levels 20+, depending wether or not you use type advantage.
Effective types of pokemon: Electric, water.
Ineffective types of pokemon: Fighting, ground.
Pokemon: Dewgong (water, ice)
Dewgong is beatable around levels 30+, again depending wether or not you use type advantage.
Effective types of pokemon: Electric, bug, grass.
Ineffective types of pokemon: Fire, ground, and rock.
Pokemon: Ludicolo (water, grass)
Ludicolo is beatable around levels 40+, depending wether or not you use type advantage.
Effective types of pokemon: Electric bug and poison.
Ineffective types of pokemon: Fire, water, ground, rock.
Pokemon: Gyarados (water, flying)
Gyarados is beatble around levels 50+, depending wether or not you use type advantage.
Effective types of pokemon: Electric, bug, flying, and grass.
Ineffective types of pokemon: Fire, ground, rock, fighting.
NPC: Sparky Pokemon: Electivire
Beatable at 60+, Depends on Type advantages or catch a wild Heracross and use that.
Effective Types: Ground
Ineffective Types: Water
Pokemon : Gengar (Ghost)
Effective types of pokemon: fire,psychic,
Ineffective types of pokemon: grass,ice,bug,flying,
NPC: Atlanta Pokemon: Wailord
Beatable at about 60-70, Depends on type advantages.
Effective types of Pokemon: Electric, Grass.
Ineffective types of Pokemon: Fire, Ground, Rock
After beating all 8 gyms, you are elligible to battle the Elite 4.
More info about the Elite 4 can be found by clicking the link.
Where can I find these gyms?Edit
1st Gym (Brock and Onix ): The first gym can be found at the end of the huge forest at the starter map. Simply enter the forest, turn right, you will find Brock waiting. Speak to Brock to battle Onix, to unlock the cave.
2nd Gym (Falkner and Pidgeotto ): The second gym can be found at the end of the first cave. At first the cave may seem confusing, but after awhile you will get used to it. Head to the end of the cave, and you will appear at Falkner's gym. Walk across the bridge and talk to Falkner to spawn Pidgeotto.
3rd Gym (Athrun and Dewgong ): The third gym can by found by entering a doorway from Falkner's gym. Head up the escalating path to get to a snow/frost covered ground. From there, enter the gym and speak with Athun to battle Dewgong.
4th Gym (Erin and Ludicolo ): The fourth gym is a bit difficult to find. Enter the Waterfall area, then climb up to the Pokemon Center (healing station). On the right of the healing station there is a doorway which leads to a cave. This confusing cave winds up, down, and around. After braving the cave, you come to a new area. You have to climb the slanted poles to get to the gym where Erin and Ludicolo wait.
5th Gym (David and Gyarados ): To get to the fifth gym, make your way up the slanted poles to a doorway high up. Upon entering the doorway, a large map filled with lava appears. Follow the winding rocky path. If you accidentally fall off, it's okay, the lava doesn't kill. Just head back to the start of the rocky path. When you reach the top of the rocky path, enter the door. You will find yourself on the shore. Head towards the gym and speak to David to battle Gyarados, or head up the grassy platform to heal your pokemon at the pokecenter.
6th Gym (Sparky and Electivire ): The 6th gym lies beyond the Waterfall area. If you are at the 5th gym, head back to there. From the Waterfall area, make your way across the wooden bridge, and take the door on your left. The Shore Badge is needed to enter this doorway. Once entered, you will once again be in a forest. Go to the end of the forest. There will be a door, and will teleport you to the construction site. In front of the construction site, Sparky and Electivire wait for any challengers.
7th Gym the seven gym leader is friend of the 8th gym leader.this gym could only find on an island.
8th Gym this gym will be found the other side the cave or you could ride the subway.