A trained fighter easily beats an untrained fighter. Roger Huerta brutally dispatched with ease a division I college linebacker that had 8 inches and 80 lbs on him. Khabib Nurmagomedov would easily kill any untrained gymmaxxer on the planet in unarmed combat (proof of that:
https://www.dailymail.co.uk/news/ar...-killing-weightlifter-bare-knuckle-brawl.html ).
The reason weight divisions exist is because a larger
elite fighter will beat a smaller
elite fighter. However an elite smaller fighter will easily beat lower ranked and unranked fighters even giving massive weight and height advantages, let alone the completely untrained.
Guy on the left (Randy Couture) was winning for almost 10 minutes of fight time against the NCAA division I HW wrestling champion and multiple time all-american on the right (Brock Lesnar).