dude ok i understand ur point but itachi can also win against pain, there are not many scenarios that pain can win in. look preta can easily be stopped by sword, tendo can be stopped by sword or stopped by itachi using genjutsu on him, others are vulnerable to ninjutsu like amaterasu, yaska magatama, and itachi's fireball techs. And itachi can pretty much defnd any of their attacks with yata mirror. YES pein can win he is really powerful with his paths but i see itachi's chances are better due to his ultimate defense, his sword, amaterasu and intelligence which he has shown us from time to time. If itachi sees their ablities he can would kno which ones to take out first. itachi IMO has a better chance in winning i am not saying pain cannot win.