That would be a reasonable strategy, but remember your ghost type will be weak to your opponent's moves, as well.

Ah, though it said your furret knows Foresight? I believe that will allow its normal and fighting type attacks to hit ghost types, if you use it. Mirror Move would also work to copy useful moves, but since fearow is part normal type, it's unlikely that the gym leader would attack it with ghost moves in the first place. Also, making use of moves like Attract and such can make it difficult for your opponent to attack you.