hearthome gym

You have got to follow the guy in front of the entrance to the great marsh talk to him(galactic member) he'll run off find him and talk to himhe will be going towards te lake near passtoria from pastoria. Keep talking to him until he battles you. Mext cynhia comes and gives you secret potionfor the psyduck above solacion. The path will take you to celestic. You will need defog. When you get there you will battle another galactic member give the old charm to cybthia's grandmother and go in the cave. Then you can battle Fantina

What you have to do is head over to Pastoria City, and find the Team Galactic member that is there. Near the entrance of town, you will see a Team Galactic member standing there so talk to him and you should battle him, or he should run off. Follow him and keep talking to him until eventually, he battles you. After you defeat him, you should be near a Lake of some sort, and Cynthia should give you a secret potion that will get rid of the Psyduck's headache north of Solaceon Town. After you do that, head to Celestic Town and save everyone there from the Team Galactic Member by battling him. After that, you should be able to go into the gym.

Hope this helps.

You need to chase the team galactic grunt near Pal Park up to Lake Valor with a rival battle in between, once you beat him, you will see Cynthia who will give you a spray to move the psyduck blocking your path, continue to Celestic town and speak to the old woman outside of the Pokemon center. After that go to the cave nearby and defeat the galactic grunt, the old woman will walk in afterwards and you can give her the old charm you got from Cynthia, after that you should be able to get to the gym.