How old is he? How old are the hens? To me it sounds like you have a young immature cockerel, not a mature rooster. And the hens are probably mature hens, not immature pullets, though they could be pullets that are just more mature than the cockerel. I'm guessing, of course, but it sounds like those stages of maturity. I'm not even sure he is old enough for the hormones to have started flowing, he sounds like a really young cockerel.
At some point the hormones will start flowing and he will show an interest in the hens. Until then he is just another young chicken to them. So yes, it's a normal integration for now. Hens tend to pick on young boys more than young girls, but at a very young age not that much.
Once the hormones start flowing he will want to mate with the hens. Some hens, even mature ones, will pretty much squat for anything wearing spurs, but very often a mature hen is more discerning. She wants a rooster that treats her right, dancing for her and finding her treats. She wants one that keeps peace in his flock. He needs to have the self-confidence and self-assurance to WOW! her with his magnificence. In other words, she wants a rooster that will make a good father for her chicks, giving her strong healthy chicks and managing his flock so they have a good upbringing.
When those hormones hit he will want to mate with the hens. He will likely be as big as they are or more likely bigger. He will probably try to force them. The hens will probably not want to have anything to do with him, they may fight or they may just run away. It can get pretty wild down there at this stage but I've had some transitions in dominance go very smoothly. At some point he reaches a maturity level that he dominates them and they accept his dominance. I've had males as young as five months manage that, I've had some males still not having won over all the hens until 11 months of age. It's a matter of maturity and the personality of your cockerel and the hens. The personality of your individual hens plays a part in this too.
If you have an already fully mature rooster the best way to introduce him to an all-hen flock is usually to just toss him in. He mates with a couple of hens to show he is boss and he WOWs them with his magnificence and self-confidence so they usually accept his dominance with little and sometimes no resistance, and life is very soon good. However, with a young cockerel Azygous's method is probably the way to go. Just give them as much room as possible, now and in the near future. Lots of room helps with behaviors.
Good luck!
