I see kisame and itachi losing because konoha when dealing with pain had 7 opponents+all of those summons (the six paths and konan) so Konoha's forces need to be spread throughout the village. now picture all of the jonin+ a few s class fighters all ganging up on kisame and itachi. kakashi,naruto and tsunade alone are enough to give itachi or kisame trouble. konoha still has shikamaru and shikaku to formulate strategy's to counter there ability's. You need to take into account that all jonins are still really skilled and both kisame and itachi will need to do more then just throw a kuni at them.Being strong is not in advantage against so many opponents stamina is necessary. Two invaders compared to seven is a huge difference konoha can easily overwhelm the two of them no problem.