ChivalRuse
Smash Hero
I don't think he has to have "untapped potential" to be tournament viable. On paper his biggest flaws are his lack of KO setups and his lightness (I don't rank his lack of range as a major enough flaw).
As far as KOs are concerned, you just have to become a master of his few KO opportunities.
The lightness issue just means you have to avoid the most threatening moves that can KO you. Obviously, you can't indefinitely avoid them (eventually you will get grabbed into a fair or uair). But you can still make your opponent work really hard for it. And at the end of the day, that's all you can do with any character.
As far as KOs are concerned, you just have to become a master of his few KO opportunities.
The lightness issue just means you have to avoid the most threatening moves that can KO you. Obviously, you can't indefinitely avoid them (eventually you will get grabbed into a fair or uair). But you can still make your opponent work really hard for it. And at the end of the day, that's all you can do with any character.