Depends on if you can corner them. Straight boxing? No, they live on combos and escaping but let some big 200lb nikka close the gap and knows how to throw a punch, he has a chance. This is strictly street fights, so the answer is yes can stand a chance in a street fight where you may have a significant size and strength advantage. If you're of similar size then no way.
If we boxing he got It... If it's a street fight..he is getting choked and slammed.. flyweight is like 5'4 110 or something