I am learning a lot thanks to you all!
I forgot to mention Tyranitar. Is it too strong for high prestiging?
I think a good Fighting type like Machamp with Counter/Karate Chop Close Combat combination would be able to beat is despite a lower CP.
It does 1,56x damage and receives 0,64x damage.
Unfortunaltely I don't have a good Machamp yet to try it out.
Or a good Ground or Steel type mon?
Maybe even Water or Grass types?
Let me hear your ideas/expericiences with prestiging against a Tyranitar.