Roy Jones Jr. vs Floyd Mayweather Jr. and let's say that they're in the same weight, who would win?

Mayweather. Geeza just knew how to win fights no matter who it was didnt really have a prime as he was always in it. Loved watching him early 2000s. As he got older and hands started playing up he adapted his game and still won albeit and a less enjoyable way still loved watching it though.

 

In that case, Roy by stoppage.

Floyd has exactly 0 chance.

He has no way to outbox Roy from the outside with RJJs 3 inch height advantage and far longer reach and way faster speed at 154. If floyd tries to get on the inside, 1) he sucks at it, look at him trying to get inside vs a taller opponent in Mcgregor, 2) he would get folded with a body shot or ktfo with a combination.

finally, Floyds shoulder roll is practically useless against a taller opponent who punches down and not up. The shoulders are below his head, when opponents punch up, he blocks it with his should before it gets to his head. If the opponent is punching down, floyd has no way to block that punch with his shoulder, if anything, he’ll block the shot to his shoulder with his head.

which is why guys like Tommy Hearns would have stopped him inside 3 and PW would probably have overwhelmed him.