Decidueye

Sun: It fires arrow quills from its wings with such precision, they can pierce a pebble at distances over a hundred yards.

Moon: Although basically cool and cautious, when it's caught by surprise, it's seized by panic.

Ultra Sun: It nocks its arrow quills and shoots them at opponents. When it simply can't afford to miss, it tugs the vine on its head to improve its focus.

Ultra Moon: Decidueye can nock and fire an arrow at an enemy in a tenth of a second, so its battles are decided in the blink of an eye.

Sword: As if wielding a bow, it launches the arrow quills hidden among the feathers of its wings. Decidueye's shots never miss.

Shield: In a tenth of a second, it can nock and fire an arrow quill, piercing an opponent's weak point before they notice what's happening.

Legends: Arceus: The air stored inside the rachises of Decidueye's feathers insulates the Pokémon against Hisui's extreme cold. This is firm proof that evolution can be influenced by environment.