The Flying type has been completely reworked.

Corviknight and Cramorant are both primary Flying because Flying is no longer necessarily a secondary type. Before them, Noivern was the only dual-type primary Flying because it both flies and uses sound (Boomburst) as a primary attacking method.

Normal/Flying types have mostly all been changed to pure Flying (Fearow, Swablu). Chatot, Pidgeot, and Swellow are now Flying/Normal. Dodrio is pure Normal. Braviary is in the game and is now Flying/Fighting.

Sirfetch'd is pure Fighting. Like Dodrio, it doesn't fly, so even though it's a bird, it doesn't get a secondary Flying type. Being a bird no longer necessitates a secondary Flying type. A secondary Normal is only used if the Pokemon has sound-related abilities (Hyper Voice, Boomburt, Chatter).