Go east to Solaceon Town.
Chat with our AI personalities
fly
hm defog
Fantina is a Ghost type gym leader, meaning normal and fighting types won't have any effect.
A trainer in Victory Road has a Gengar.
Fantina is in Hearthome City. If she isn't there. There is something you have to do before. I think you have to go to pastoria GYM first. Then she'll be available, but have been into the Pokemon contest hall before, she appears in there with your mum.