there was absolutely no point to giving them that power, when he could have done it himself... AND SINCE WHEN CAN NON SENJUTSU USERS TAKE IN A MASSIVE AMOUNT OF NATURE CHAKRA AND NOT TURN TO STONE.
and didn't a rasenshuriken with amaterasu flames do less than this nakama odama rasangan friendship > logic > story telling **** fest.
he probably could have done it himself, but he needed them so he could focus on the final attack. You only turn to stone when the senjutsu chakra is not balanced with the other chakra you have in your body. no where does it say if you take in a massive amount of senin chakra will you turn into stone. if you take in a massive amount and cannot balance it thats different. but naruto has already shown skill in balancing his ninetail chakra with peoples chakra so naruto could balance it for them. and damage is relative
Even looking at what went into the move you can tell why it did more damage
Rasengan+Wind+Fire+smaller size=Enton rasenshuuriken
Rasengan+Ninetail chakra+Senin Chakra+Bigger size Rasenganx9= KH11 Power of friendship rasengan.
Wind chakra<Senin chakra
Wind chakra<Kurama chakra
Enton>=< Senin Chakra
Enton>=<Kurama chakra
Small rasengan<Big rasengan
1 Rasengan shuriken < 9 Odama Rasengan