Captain Falcon has minor gameplay changes based on which alternate skin is being used. Presumably a programming oversight, the character's Environmental Collision Box (ECB), a small diamond that prevents the character from falling through stage environments and walking through walls, differs slightly between skins, meaning they have very slightly different widths for dealing with stage collisions/interaction (although hurtboxes remain the same on all skins). Ranked from thinnest to widest, Captain Falcon's default skin has the thinnest ECB, while the Pink, Blue, Red, and Black skins have wider ECBs, with the Green skin coming out on top with the widest.
Contributed by MehDeletingLater