if i have more ideas i will put it here...
for stages:whenever u complete a stage,they wil show u a password for a char
for everyone:when a person has less than a quater HP,their attacks becomes weaker,they run slower,and they can't stand up(unless they are run)
when two person attack each other,there will be an icon beside them asking them to press rapidly up,down,right,left,attack,def or jump,the one hu press the slowest will be hit.
for tools:-an item that poison peoples==
-throw a scroll and press attack(any other key u wan to code also can,eg. onli)and u will teleport to the area where the scroll is throw at,if u never press attack notihng will happend.
For naruto:how about when he becomes sage mode,he can only use a minimum of 2 rasengshuriken(if it is throwing one)and when he use 2 rasenshuriken,he become normal again.(meaning become normal naruto,not sage naruto)
suigetsu:he can transform into the monster,the big one.(he uses this jutsu when he was fighting with killer bee in the anime or manga)
tobi:how about when he use a jutsu,he becomes not solid and can pass through anything and anyone hu attacks him will just pass through(the jutsu is only for 20secs or so)
sasuke:he use his amaratesu as a sheild around him and no one can attack him and if anyone attacks him,they will only get hurt by the amaratesu(the jutsu is only finish until he has no chakra or he can stop it by pressing def)
jugo:when any of his teammates (that has a curesmark )dies,he could revive him/her to a maximum of 50% depends on how much chakra jugo has and when he finished the jutsu,he will become a kid that makes him weaker.to make him back to normal,he must use a jutsu that sucks out a dead person's chakra(i do not noe what to call it so just call it chakra HAHA)and he will return back to his normal self,but his HP will not recover.
deidara:he uses C5/4 (do not noe which one)when he is on the dragon and eat all the clay and he make a big him and explode and those hu go near it will just die.aand he will be able to use any justu anymore as he no clay,only when he eats the clay from the dragon(the dragon will just stay at the groung it will not disapear)
nagato:he can't move and u uses the sharp thing that is dark in colour n shoots it out to a died enemy or partner and control them,when someone kills nagato those people that are being controled will die.
he uses a jutsu that will revive all people but he will die.
orochimaru:he uses a jutsu and becomes the white snake,he uses a jutsu that does the ritual and uses all his MP and it takes 20sec.(it can be only used in snake mode)if anyone defeat the opponent before the ritual finish orochimaru will die.
kakashi:LVL 1-sumoning the dog to attack,lvl 2-trap the person by biting him and it also injured the enemy,lvl 3-kakashi hits the person up and the dogs the enemy crossly.