Even Naruto, who as the central (not to mention title) character should be the most powerful (them's anime/manga rules), loses sometimes. I don't think Sasuke's lost once.
Not rly. I can't think of a show where the main character=the most powerful. Usually the main villain is, and they die by some fluke. >_>
What I mean is that the main/title character is usually the one that wins all the time. Not the rival.