Anyone that could put him down with one punch will be weight drained. Pacs so scared to fight Martinez at 154 yet he fought for the 154 title against Margo.....see how Pac is strategically cheating here. He should man up and stop being a *****. But instead of facing reality you will just say something like Floyd beats his mother.
No shot. He is tailor made for Manny. Floyd is so used to controlling the pace vs older Welters. it would almost be like him fighting a different style like MMA. All the looks he would see would be nothing he is used to. His cherrypicking would help Manny throw him off even more as the speed and power would be heightened just from the opponent differential. Floyd already has very subtle trouble early on figuring out vanilla fighters. Manny would be a tough nut to crack for him and the inactivity and lack of power would surely overwhelm this made to order hype job. Let's not forget he has been shitting in his pants about this guy for almost 2 years. His reflexes even a nanosecond off from the Mosley fight would lead to a shocking outcome.
Floyd is the obvious choice but I think he has "0" chance because doesn't to take the risk of parting with the "0" on his fight records.