Why would Muu even be considered being in? I just don't get it. Muu isn't even heard of until the War Arc, let alone fighting until about like ten chapters in. The game goes up to, by appearance, all the way through the Summit, and maybe Confine the Jinujurriki. Muu, and people like him, aren't seen till way later. The nine tailed Naruto mode is a huge surprise, but I think he's like Lars. A special unlockable. Anything could happen though.
Karin......If she is playable and the Sound 4 aren't.....I'll die on the inside. Similar to how I am with the Darui issue. LET'S ALL PLAY AS KYBUUI NARUTO WHO SPAMS RASENGAN/RASENGANSHURIKEN AND KARIN, WHO'S NEVER BEEN SEEN FIGHTING, INSTEAD AS DARUI, WHO IS KUMO'S NUMBER ONE BADASS! Seriously CC2....what the hell? xd
Atleast, this is what I think anyways. This game could have anyone, but CC2 is keeping it all close to their chest here.