After playing Nariko in a few matches, I can say with confidence that she is in no way underpowered, or at least not by the stretch people claim she is. In fact, I think people think she sucks only because spamming square will not earn you 60-90 AP per combo. That being said, I do think she needs only one buff to be balanced, and that's a slight movement speed and jump height buff during her level three super to catch people that get above her. That's about it, I honestly love this character.
I feel like if she had a decent level 1 hit confirm she could be top tier. I got a chance to play against a good one and she is difficult to approach. She can easily burst combo you out of the air. --- PSN: Potatoman622 Fear the Fabulous Fatty P