I had one that was just a bully. With free range of about an acre, she would literally chase them all over terrified, they'd run into the coop screaming, crying, trying to crawl into the corners of the nesting box and she'd come in and tear feathers out and eat them and tear holes in them. I seen her do this twice. The second time I grabbed her and wrung her neck. I will NOT tolerate abusive bully's. I get the pecking order thing but to chase across the yard to attack a young one. NO.
Had another one who liked to be a bully, she was not THAT abusive but would go out of her way to be mean. She got a week timeout. She lived in a small cage, with food and fresh water of course, while the rest of the flock, including the new one, all lived and got along and situated in the coop. They got to free range, she got to live in the cage for a week watching them free range. Oh she was not happy and very vocal about it too! When I finally let her back out, it was like she was the new one to the flock, and the bullying stopped. From that day forward, they will nip at each other occasionally but all get along.
Recently added two young ones. ie two 12 week old birds to a flock 2 plus years old. They stood their distance for a few weeks, and slowly made their way into the flock. A few times some of the... I take that back, ONE of the older girls tried to show her ass, she promptly got it paddled. YES I lifted her tail and gave her a nice swat and then held her back and made her watch while everyone else ate, including the new girls. THEN she was allowed to eat. it only took twice then she learned not to snap at the little ones. Fast forward to about a week ago, I had problems with a few of them not wanting to go into the coop at night and I have to go round them up and put them on their roosts. (don't get me started on spoiled rotten birds

) well I went to do a butt count, and usually the 2 lil ones would sit on the edge of the nesting box while the big girls were on the perches. Well I look in and all 5 are on the roosts, all mixed in, no 3 here 2 there, so it was at that point I realized, ok, they are all ONE flock now
They will bully from time to time, they will fight from time to time, and sometimes you got some who will make it a daily thing to nip or peck the entire flock to let them know who the queen is. If the problem is severe, cull the bully IMO. Sometimes the bully can be isolated and then returned and, well, in my case, it worked.
This may sound like im totally off my rocker but...from my experiences.. Red birds, tend to be more bullysome than the other colors. We will count golden comets as 'red family' for this. More drama, more apt to bully others. the black colors, tend to be more defensive, accepting of the new girls when they are brought in. my black ostalorpe actually stepped in to protect the little ones a time or two and she's normally towards the lower end of the pecking order.
As far as roost wars, every day I look in there it seems they are in a different sleeping pattern. The biggest kerfluffle is when one of the late comers hops up and smacks into one of the ones up there already or knocks one off, who then has to hop back up, then there might be some drama but otherwise once they are on the roost, the games are over for the day.
aaron