Use your jab to pin his hands before atacking in order to avoid a counter punch after your attack. Dodge always after hitting, even if you are not expecting a punch, and get out of the distance using an angle if you can. If you miss punches you committed with, use your forearms to pin his gloves to avoid his counter punch. You can block his head too, controling his head is highly effective to avoid a hard counter. If you are being attacked use your rear hand to pin his gloves or control his head and pivot to make him not able to throw a clean punch. If he has the same stance as you do, keep occupying the space with your rear hand to make impossible for him to throw a clean strong-hand punch. If he is not in your same stance, touch his rear hand often with yours or keep it close, as soon as you feel any kind of movement or feel something in your rear hand, jump back and leave him out of the distance (fight back if you can) Stay out of the distance unless you are attacking. Try to control the tempo of the fight with a pot jab, make the tempo to be regular and as slow as possible, then change to a much faster tempo when attacking so that he can not time you. I he attacks while your pot-jab, use it to control his head, pivot and occupy the space with your rear hand so that he cannot throw a clean punch with his strong-hand. Actually... all that is just boxing. Floyd is god doing all that stuff. Ward is a master controller too. Rigo is your guy if you are southpaw. And barthelemy if you want to know how to control a fight's tempo, he does it pretty well.
One way is to move in closer and jam him up. Some powerpunchers (not all) rely on a certain amount of spacing to throw a punch. So by getting in close when he's about to throw a punch shortens the distance and throws off his ability to leverage the punch. Some powerpunchers are used to throwing short hooks and uppercuts on the inside, so if he adjusts well to distance, then this might not work as well. Plan B is to use a powerful punch, I call....the "nutter-cut". It's like an uppercut, but.....you get the idea.
Lol, that depends on the man you're facing. Some fighters need to set their feet before throwing with power, so boxing and moving in a direction away from the opponents power hand can work IF you are faster of foot and quicker of hand AND your reach is equal to or greater. Another way to do it is to fight very close and smother his punches...but you'd better hope he doesn't have an upppercut. Finally you can always use the John RUiz clinch and jab style. If none of the above works, your own offense if you hit hard enough can deter a puncher.
Use your jab to keep him off balance and move around the ring alot so as to make him chase you down. This will wear him down seeing as to he's using all power punches. Remember to go to the body alot as well.
I suggest watching Peter Quillin vs Andy Lee. They both have power and knew it so they tried to find a way to neutralize it.
You can smother the power by getting inside or neutralize with a jab. If you are a good jabber create a mental box in front of your targets forehead and paw/throw half punches at it to keep at distance. Once you see an opening adjust the target through your opponents head hit score forcing them to reset while you pivot out. You have to have good technique and speed to do this. As with any other style getting off first will hinder your opponent.
Some people think you have to fight on the outside with a jab to neutralize puncher. I prefer Andre Ward's approach when it comes to punchers. Get on the inside and take away the range and effectiveness of an opponent punch. That's why I was laughing my ass off during the super six tournament final when some where predicting that Froch will KO Ward if he ever tried to fight him on the inside.
A lot of it is geometry. A lot of pivots and good footwork to keep yourself from being squared up in front of the guy. After you punch, always step off a little to one side or the other rather than standing there 'waiting for the receipt.' Another thing that I think gives a lot of big punchers trouble is constantly changing the level of the target -- which is to say not keeping your head at the same height all the time. Bend your knees slightly (or even more than slightly if you get comfortable with it) and spring up to fight taller from time to time so he's always guessing whether to punch up, down or level. Both of these take a lot of practice.