Would you say Cottos left hook is as effective as Fraziers/Tuas/Tysons?

I think it is. Cotto has a very large amount of KOs and most of them came mainly as a result of his powerful left hook to the head and body. He is left handed and his left hook is one hell of a punch. Just ask Geale. Cotto knocked the iron jawed Clottey down with a left jab which is also a great punch. That shows the power he has in his left. His left hook combines speed with getting his body into the punch.

No, if he KO's Canelo or GGG in a round then maybe you can compare him to Tyson, Tua or Frazier. Those guys were throwing bombs that could kill a man, Tua KO'd John Ruiz in 19 sec and Micheal Moorer in 30. We all know Tyson was the king of the quick KO's. Cotto couldn't finish off Sergio early and the fight went 9 or 10 rounds with Sergio doing nothing, the 3 fighters named would have won in the 1st or 2nd round against a shot and ring rusted fighter. Cotto is good but Rodriguez/ shot Martinez/ Geale fights would make ANY good fighter look good.

Maybe the headbutt, left hook combination

As already stated it wouldn't be fair to compare Cotto's lefthooks to that of heavyweights. Now comparing his left hook to previous Welterweights ala Tito would be more appropriate. That said, Cotto's lefthook couldn't break wind compared to Trinidad.

You can never say any fighters punch is more "effective" than a heavyweights, ever! It will never carry the same weight and power obviously! What I will say is Cotto's left hook is technically more refined than Tua's, Fraziers and Tyson's.

Then Golovkins hooks are Jesus Christ level, right? If so, then I accept the comparison. Haha I might have to agree w u bud. But GGG is a KO artist. Cotto is more a boxer puncher but when he Lands that left hook clean then it's usually done for. That's all I was trying to say. But u right both GGGs hands like a freak of nature

No, those guys would position themselves a lot better, they would slide to their opponents right when they utilized theirs.

Then Golovkins hooks are Jesus Christ level, right? If so, then I accept the comparison.

http://33.media.tumblr.com/f139300267dec92b483615c9ead854bb/tumblr_inline_nnw6g6tNU61r2yao7_500.gif

ive just rarely seen a fighter KO so many people with that same shot. Whether Body or Chin if he lands left hook flush the end is usually near. I haven't seen such a dominating L Hook since probably David Tua most recently. But there were many before that Joe Frazier/Joe Louis/Mike Tyson, lots more. But do you think Cottos left is as devastating as those others? No because they were all heavyweights. Pound for pound is it up to par with theirs? I would say yes. All of those punches can turn/end a fight and so can Cotto's.