Aerodactyls are not able to be caught in the wild. You get an Aerodactyl in Fire Red and Leaf Green, from the Old Amber fossil you find behind Pewter City's Museum. Go to Cinnabar Island's Laboratory and the scientist will revive Aerodactyl for you.
As far as I know Fire Red and Leaf Green can export Pokemon to Diamond, Pearl and Platinum. You can also trade with Sapphire, Emerald and Ruby.