Edo Itachi beats DSM Kabuto. But let's clear up some things before we start.
Itachi used Izanami on DSM Kabuto. It's mimicked as full-on paralysis of the body while the conscious contemplates his/her existence. This only works if: 1)The victim does not know who he/she really is 2)The user has knowledge of this
So you can say that Itachi + Preptime can defeat DSM Kabuto. But if DSM Kabuto never uttered a word and engaged in combat, then Itachi would lose.
Edo Itachi has no problem with defeating DSM Kabuto, however, because of the bonuses of being an Edo that completely eliminates Itachi's weakness--stamina.