are you faster then most of your opponents and can you kill1-2 ninjas round 1? dont use one
are you slower and need to survive the opponent attacks, clear debuffs before you can do any significant damage? in this case use at least 1
it doesnt need to be a healer, it can be a support character like iruka that gives high shields, or danzu that can chaos, or even fire main with shield plus immunity to debuffs and so on.