I know Ice Climbers had a more original moveset, but Mewtwo was far more popular outside of Smash. Ice Climbers may as well not exist outside of Smash, as far as 99.9% of people are concerned they may as well have had their first role in Melee.
If the moveset isn't a cloned one, then the uniqueness of the moveset shouldn't matter. I suppose that means the Ice Climbers are the most deserving character in the game followed by Olimar and the traine due to having a unique moveset. </Sarcasm>
I don't care if Wario and Yoshi have their own icons, they're part of the Mario world. Yoshi doesn't deserve to be considered it's own series, and it was a most random choice by Sakurai to have it be so. Wario is understandable, he has his own real series, but he should still count as a Mario character. In the long run, nobody cares about how many characters bare the icon of the series, it's about how many characters are actually from said series. Pokemon is more popular, famous and well known then Zelda, and Zelda doesn't have a fifth character nearly as deserving as Mewtwo.