Itachi didn't kill Uchiha Clan Alone he ask for help and Madara uchiha help him !!yes u'r rgiht but don't forget that itachi can copy kakashi's jutsu as well and besides i think if u can kill u'r whole clan which was supossed to be the greatest along with the senju you'have to have experience and be very powerfull and if it comes to who has more chakra itachi would win just because kakashi hasn't much chakra.I think it would be a great battle 2 see and kakashi definetly would give a very good fight but in the end he would lose