While I do agree pokemon like scyther should be able to fly, I see nothing wrong with pokemon like pidgey using it. If a Braviary can carry an automobile without hindering it's flight then why can't a rufflet pick up a human in it's talons and carry them. They're pokemon so their strength isn't that of normal birds. As for Arceus and mew, Arceus is the God of pokemon, while Mew is who they descended from previously so I see nothing wrong with it. Volcarona, and Hydreigon both have wings, and Genesect can fly as well as it was recently revealed.