Justin dominated a major with Iron Fist. Want me to keep going?
Now we're getting into semantics.
1: He was using Iron Fist when the game was still fairly young.
2: It's Justin Wong in Marvel... Come on.
3: It's Marvel, you could do well with practically any character if you have the right team. It doesn't apply to KOF.
4: Jwong was using Athena when the game was young and there weren't high level players that knew what they were doing. As soon as he used Athena against people who knew KOF he was done.
5: To use a 3rd Strike example. Just because Kuroda or TM are absolutely amazing Q players that do amazingly well in tournaments and Ranbats doesn't mean that Q is a really good character. Q is a really bad character and it's a struggle to win with him even if you know what you're doing.
Take for example Bala using Joe. You can't say that a character is good just because a gdlk player will use him from time to time. Bala is at that level and can make Joe (a relatively low tier character, let's be honest here) work for him. How many other people have done nearly as well with Joe? Just saying. I'm not saying Joe is bad, but it can be hard to win with him.