ok so I have been thinking various different kind of power one can use while writing isekai story or reincarnation story but all of them have been used by some one or has not many use this limiting the user . Whenever I thought about person reincarnated in Animeverse or any kind of world I imagine him helping every character to develop to there full potential but all power I come up with either make them strong or simply put are not useful for helping other character dovelope more. Imagine kakashi if he hadn't been traumatized by his team mate death and moved on . He could have become far stronger than in present timeline , remember kakashi rapid improvement in war arc it was all possible due to prodigious talent and effort he put due to war but if had his trauma cured then he might worked harder since early age and surpass him in present boruto series long time ago thus first ability I come with is "All Heal " it work as its sound ,heal all kind of wound whether mental , physical or in soul . This ability is most useful in naruto world as majority of character have serious trauma issues including itachi , sasuke , madara , tsunade etc imagine if tsuande trauma was cure after nawaki death or den death she would remain in village , even orochimaru who want to become immortal all because traumatized from his father death or danzo who become full on paranoid and shit.
Then come power which inspire me from dragon ball z but it also have fandom page in superpower wiki i.e. "Potential manipulation "
as it sound it let user to control potential of someone he could even unlock hidden potential of that person or his as well increase potential someone have such that person can help any character without themself noticing, imagine someone keep increasing might guy potential and might guy keep training he will surpass himself with 8 gate with time . Not only that one someone potential increase there body change in genetic level as every person are born with fixed potential and thus we get all coming generation with high potential.
p.s.
My grammar may be bad I don't because well u know the reason because it seem good to me and no one ever pointed it out so If u feel like pointing out please do so .