There are plenty of reasons to think of Yang Guo as a relatively unique character. Recently I have been thinking, he should be the only protagonist who created his own martial arts system. Not from scratch, but nevertheless he "glued together" the stances and made it his own. And he even did it within the novel's scope. How many people have done that, out of every character in Jin Yong universe? OTTOMH (off the top of my head) I can only think of Zhang Sanfeng and maybe Zuo Lengchan (I'm sure there are others, but probably only a few more). Most of the martial arts were invented OFF SCREEN, before or after the novel's scope. Yang Guo actually invented a martial arts during the story. I think that he may be, chronologically, the first person in Jin Yong universe that we see achieve this in the story. When did the other Greats invent their own martial arts?