And since you are wanting to breed for pets as well. Males as well as females should not bully others. There will be some sniffing and shoving and the little boy may squeak because he is frightened and letting them know he is uncomfortable. But there shouldn't be any true fighting or squaring off, IMO.
In my experience, males who are bullies will bully their established females as well. I had a blue male that every time I cleaned tubs and he got worked up, he would harass his females.
Bottom line, no one should give you issues.