Water, Electric, Ice, steel, and rock are all super effective. Keep this in mind when choosing a move.
omanyte and anorith and aerodactyl
Im pretty sure you dont catch aerodactyl in heartgold but I think you can get him as a fossil, if you do, talk to the guy in the pewter city mueseum and he will turn it into aerodactyl for you.
If you're talking about an in-game trade, then no.
Get a old amber and take it to a guy in the museum in Petwer City,
Beat Red
That'd be Aerodactyl which appears in/on the Peril Cliffs once you beat the game.
arceus will beat him easily.
Do you have every Pokemon in the game? If not, NO!
That depends on which one you did fourth. You can do them all in different orders. It may be the Aerodactyl puzzle.
Ice type Pokemon can easily defeat lance's Pokemon also for his gyrados and aerodactyl you can use an electric type.
you batle them
you get it AFTER you beat blue