It sounds like you have an extremely DOMINANT Roo,
Did you try and introduce them well? I had a Roo and just put him in with the the other hens and he did just fine, i figured he would be okay because he was mild-Tame. There was a bit of fighting, but nothing too horrible. Just establishing the pecking order. On the other hand, your Roo needs to learn some manners. I would start by trying to isolate him in a cage or somewhere away from the hens, let the pullets eat while the Roo sits there watching, I would do this for maybe 2 or 3 feeds. I surely wouldn't put my Roo anywhere near pullets. Give the pullets time to establish there pecking rank, and them getting comfortable with one another. Even if there 6mnths old they need to be like pals.. All this time keep the rooster as far away as possible. once the hens are maybe 8 months or a year. I would put the Roo's cage right next to the pullets house. Let them observe eachother ad them attempt to bringing the rooster back into the cage. THink about this: Your with your friends ad all of a sudden a big scary guy comes into your house and is being a bully? Would you like that? I def wouldn't. I know its very slow going, but its better than watching your roo destroy the pullets. And your Rooster must learn to Respect the hens.