If sharingan is lvl 1 and rinegan is lvl 2
Then how lvl 1 can beat lvl 2 ??
Did you know how you can have rinegan ??
And did you know how to get sharingan??
itachi already did U_UYes! so do you think itachi can solo the likes of nagato?

Neither of your questions are answerable. No one but Kishimoto knows that information.