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The Flying type has been completely reworked for Sword and Shield so that it's more like other types--it's no longer a secondary type by default
Corviknight and Cramorant are both primary Flying types because their abilities focus more on flying than on their secondary types.
Most Normal/Flying types are now pure Flying. Fearow, Dodrio, and Farfetch'd (which is why Sirfetch'd is pure Fighting) are a few examples. Chatot and Pidgeot are now Flying/Normal because of their affinity with sound (Chatter and Boomburst, respectively).
Mantine and Gyarados are still both Water/Flying because they are aquatic. Wingull is Flying/Water like Cramorant because it lives in the air.
Flying is finally a real type.
Pic unrelated.