What would be the weight division of current top fighters if . . .

guys, my assumption here is same day weigh-in is not exactly the same as fight night weigh in. it can be the morning of the fight with around 12 hours to rehydrate. so there is still time to recover but it will be a lot less the weighing in the day before. I think big boned fighters such as Canelo and even Cotto (the WW one) will be the ones who suffer the most. Floyd, Pac, GGG, Hopkins and the likes who never really blow up in between fights will just be fine.

fight nigth weight is not a proper way to determine their weight, They just splurged on food and liquid and their body soaked it up like a spunge from all the dieting they been doing for the last few months.. the 30 day weigh ins will be more of a precise weight to go by.

the same day weigh-in is brought back? My purpose is just to determine the probable weight division a fighter ideally/should belong in and not to start a case of bringing back same day weigh-ins. I think Kovalev will be CW. Ward a LHW. GGG SMW. Canelo MW/SMW. Cotto JMW. Pac JWW. Simple rule of thumb; 10 pounds to the weight classes, with modern nutrition/ S&C, should be manageable. Doubt that Kovalev makes 175, Ward still makes 168, Golovkin can likely still get to 160, Canelo moves to 160, Cotto sticks at 154, and Pacquiao fights at 140 (the weight he should've been at anyway).

That would be awful for someone like Kovalev. He'd have to move up to cw fighting those monsters. I think he'd probably still try to make 175.

Yeah, basically everyone moves up. And a couple guys (cotto and pac) are brought down to where they belong.

You have everything wrong. IF you ever looked at how much they weighed coming into the right, it tells you their weights. Ward is a CW, GGG a LHW, Canelo a LHW, Cotto a SMW and Pacquiao a MW.