The Strongest Kakashi Of Naruto

On the Night of the Nine Tails, the soul from the present world merges with Kakashi's soul, giving birth to an entirely new Kakashi Hatake

Blue Shao? Not a problem, there will always be more. The limitations of the Sharingan? Not a problem, the advanced Rinnegan is not a dream.

Ultimately, Kakashi is the strongest ninja