does it even need to be thought about? pirates were just a bunch of sailors allways drinking beer and whine and drunk like idiots with a couple of weird shaped swords
dude ninjas would :censored: own pirates they can throw ninja stars pirates can not and their identity is conceled so the pirate would have no clue who he was fighting, one more thing pirates monolouge (talk about your demise) where ninjas do not therefore ninjas would win