The third gym is Fantina's gym and she has ghost Pokemon. As long as you have a Pokemon with bite or crunch, it should do okay. Otherwise, you could just use a Staravia. Since it is part normal type, all ghost type moves are effectless. One thing to look out for is curse. It will take out 1/4 of your max hp EVERY TURN! Bibarel might do good.
you can do about anything after you just cant beat the gym leaders again.
you go to sunyshore city and beat the gym leader
go to hearthome city
lv 30
you go on to the next gym witch is etrake city
beat the gym leaders
Go beat the fourth
beat gym leader Candice
beat the heart home gym
Go to the veilstone gym and beat maylene.
umm...you beat the 7th gym
You use your strong(est) Pokemon to kill the Gym Leader's Pokemon.
you must beat the eighth gym leader and he will give you the badge.
beat Fantina in the hearthome city gym
beat bryon in the steel gym, canalve city
it's the 3rd badge!
you can do about anything after you just cant beat the gym leaders again.