They don't fly, they jump really high.
They can use Fly, though. I doubt you can explain a Doduo getting you straight from Pallet Town to Lavender Town by saying, "It hopped there!
Haven't you ever seen one fly in Pokemon Stadium? It just kinda kicks it's legs in a running motion in mid air.
Apparently they did jump, because iirc the Japanese name for Fly literally means "Sky Jump".
I guess all flying types automatically can learn fly.
^
Apparently they did jump, because iirc the Japanese name for Fly literally means "Sky Jump".