if you notice, in some abilities it says or shows signs that say tqi and nin that mean .. taijutsu and ninjutsu .... here I show that the first ability of itachi shows that it only uses NIn therefore the damage goes 100% direct to resistance ... then seeing that.

..sasuke rinne sharingan

in his passive ilution ability rinegan shows that it says "NIN" .. if the nin> res. if it does not damage to opponet.. in use ... in which the nin encompasses the ability ..., the more nin or the ninjutsu of the propip character may confuse or produce a high rate to the opponent. or just for decoration