Kakuzu has 4 hearts, I demand you have to kill him 4 times before he can truly be defeated.
Shimura Danzo performed 10 Izanagi against Sasuke therefore you will have to kill him 10 times before he can be defeated.
Aburame Torune skin kills anyone who touches it therefore any ninja phisically attacking him will die at the end of the round.
Give every jinchuriki ninja the hability to summon their beasts.
Give every sound ninja their seal transformation.
Hidan is inmortal therefore would have to create status named [Dismembering] in order to defeat him.
Onoki has mollecular level ninjutsu therefore if he hits any ninja with his mistery skill they vanish from the field and you win.
Give Snake Kabuto the skill to resurrect any ninja of your choosing that will be inmortal until you defeat Kabuto himself.


Don't forget to apply these modifications as well when working on Rinne Sasuke's rework.