Kaguya Otsutsuki is the strongest Naruto Character to ever exist. She cannot be killed. She is also the progenitor of chakra, and a Goddess herself.
It is also impossible for anyone to defeat her, as she can only be sealed. Here are 7 Naruto Characters who might be able to put up a fight against her INDIVIDUALLY.
7. Rikudo Obito Uchiha
Obito Uchiha became the Jinchuuriki of the Ten Tails during the 4th Great Ninja War. With this he gained great powers, Truth Seeking Balls, along with the chakra of the Gods. He would’ve been even stronger had he completely taken in the Nine Tails and the Eight Tails. Obito could atleast fight Kaguya on equal grounds.