I highly doubt that. Nintendo isn't one to often do leaderboards. And if there were, it'd discourage the other lower gamers (not saying I'm one of those to give up), from playing online to see how low they are in the rankings against the higher ups. While they can just play whoever they want in Friends Code mode, or just have a slobberknocker of a fight in a 2:00 minute free for all in the Anyone mode.
Besides. You can play online with a Japanese gamer, the servers wouldn't be different in terms of the quality of the online mode. At this point? I'm more inclined to believe the Roy & Mewtwo story.