The reason wolf is boxing the predalien is logical to how the pred boxed or slapped the hell out of Dutch. Wolf has obviously seen the predalien, and wants a fair match. he wants her head in his ship. The same how the jungle hunter wanted Dutch's head. I have noticed how the predators will always find the toughest, smartest, important, hardest to kill, and get a trophy. And i'm sure Wolf already has many other xenomorph sculls. I guess it is ritual for a predator to have a fair fight w/o a mask, and heavy weapons, and fight stripped of weapons, and I am sure Chet has an idea to what Wolf wants.