Well all u have to do is get blessed ninja stars/swords and go at it. cause even if ur facing a MASTER zombininja 1 TINY nic of the blade/star will utterlly destroy him while if he hits u u'd mayby be poisoned or something but u won't die right away.
Fire, Holy water, blessed weapons, a monk!! All of these are excellent methods to kill Zombies or Zombinja, or zomnjas or whatever.... Ninja make things dead!! That's just how we roll!!!
1, ninjas are immune to zombie powers, 2, if a ninja were zombified, the ninja would be smart enough to kill himself because he does not want to cause any trouble, so this wholoe ninja vs zombja thing is quite stupid