Leotis Martin vs Rocky Marciano

Liston wasn't over the hill and Patterson beat fighters over 200 pounds like Chuvalo and Bonavena. Marciano also beat fighters over 200 pounds, so it's not like any fighter beats Marciano. But you'll say those fighters don't count.

Walcott was 196 pounds in their first fight. I don't think weighing a grand total of 5 more pounds makes him unbeatable to Marciano. Leotis Martin wasn't any bigger than Walcott and was just a decent contender. Not a world beater.

https://boxrec.com/wiki/index.php/Sonny_Liston_vs._Leotis_Martin

Also boxrec puts him at 199 pounds when he fought Liston, not the magic number 200. Martin wouldn't have been anything special as far as size had he come around in 1950. He would fit right in with the contenders of the time.