Samus was the first to complete the Final Destination Match (Event 50) for me. I thought Link would win first, but only later did he appear capable, along with all of the other characters. Then, I tried using Samus to complete The Showdown (Event 51) at first, but Link beat her to it. (How ironic.) Now, I use Peach to win every time.
Samus is very powerful, but hard to use. So, of course some players will assume that she is incapable. With cunning, she can be made the most powerful character in any Versus Match. She is more than projectile attack.