Falcon - Fear of a Bird Planet
Defeat 100 enemies with feather projectiles
To make this easy go into Challenge and pick Falcon, Survival and Skrull Ship AFT. As soon as the level starts up go to the bottom middle and wait for the pillars to rise, ounce they do hold down (Y) to shoot your feathers. Doesn’t worry about aim as the game with auto do that for you, unless they are behind you. Just keep doing this until Skrull comes out and let him kill you. Now rinse and repeat till you have completed the challenge.
For this challenge I don't think Falcons Heroic attack counts only the (Y) move does.