Kakashi is double edged blade, if you are faster in round 2 or you can control your enemy, then he is amazing...
If neither of these 2 requirements can be met, then Kakashi will backfire horribly and eventually kill you...
However, Summer Kakashi with Halloween Kimimaro and GNW Madara (if you have them by any chance) can lead you into a very fatal damage in round 2.
Other option is using Summer Kakashi as support for Rinne Sasuke (if SBed)... With current heavy shield "meta" with GNW Madara and Suigetsu, Sasuke can deal massive damage, ignoring shields, which with Kakashi´s boost can be a deadly combo...