IMO "Prime Tyson" was when Cus was alive & "pre Douglas".
Then Mike didn't know that it was possible to be beat, because he couldn't be beat. <-------(true)
Nobody beats the Tyson when he was at his Prime. <-------(true)
No heavyweight in history, even in their Primes.

Nope, not him either.
None.

I will not back-off of this opinion.