how do you take the pound for pound crown..? when you are not of the same weight class..? When you are of the same weight class..?
You can't 'take it' so to speak. You can earn it over several fights. It's basically a subjective ranking of all boxers from the best down. A panel of boxing experts at the ring pick the order of merit.
Do you have a basic boxing business comprehension issue? Because if you do thats fine, theres nothing wrong with that. P4P lists are based on opinions from the general boxing community, it helps market the fighter. Usually the first two spots are debatable because its all opinion based.