Pretty much every Normal/Flying in the game could either suffice being mono-Flying, Psychic/Flying (Hoothoot line) or Fighting/Flying (Farfetch'd).
Gyarados should be Water/Dragon, but for reasons stated above it isn't (it would have no weaknesses in Gen 1 because the only damaging Dragon-type move then was Dragon Rage). Still, it should have been kept as mono Water if that was the issue. Water/Flying makes no sense, especially since it can't learn any Flying-type moves.
Dunsparce should at least be part Ground.
Sudowoodo should be Rock/Grass.
Mawile should be Steel/Dark.
Gengar should be mono Ghost, since it's not even a gaseous being anymore.
I've also never understoon why the Jynx and Sneasel line are part Ice, either.