When did I ever say it affected the range of their d-smashes? The others are just a tiny bit fatter as far as bumping into walls is concerned.The orange diamond is for dealing with stage interaction. When the movement of your character would put it through a wall/ceiling/floor or whatever, the game slightly repositions you away from that surface to prevent this from happening (otherwise you'd just pass right through them obviously).The slight difference in width of this area that normal falcon has happens to make enough of a difference here where the edge of the others' diamonds touch the wall sooner in the d-smash animation while they are moving less forward, and the pushback they get from going through the wall at that part of the attack is enough to cancel the attack by leaving the ground but not enough to fall off so they just land immediately. Normal falcon instead reaches and interacts with the wall later in the attack and is moving forward more at that point in the animation and gets more pushback because of it, and it's enough to cause him to fall off completely.