Remember it would be Kabuto, madara, Zetsu & Sasuke + Itachi, Nagato etc etc it would be about 10 vs naruto & co.
Also about the Rasen shuriken Naruto did master it in Sage Mode and until now could only use it in Sage Mode without damaging himself.
Its not an assumption its a fact as all his attributes are increased in Sage Mode and allow him to throw it.
"When Naruto is in Sage Mode, he encases the Rasenshuriken in senjutsu chakra to maintain its shape. This allows him to throw it at his opponents and removes the possibility of it damaging himself"
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