I'm no professional, but I'll add how I trained my Easter Egger rooster.
I got 20 straight run EEs and 13 ended up as cockerels. I knew I wanted to keep one, so at about 4/5 weeks old I picked out one to start training as my future rooster. I held him daily, I didn't coddle him, just asserted my dominance frequently. After only a couple weeks of socializing him and not the others, I could tell a big difference. The one I picked out was tame and docile, while the others were aggressive, and they just got worse as they grew older. At only 10 weeks old the other EE cockerels were unbearable, but the one I had chosen was still very well-behaved. I processed the extra roosters and continued holding and socializing the one cockerel. At about 14 weeks old he got a little bit aggressive, but every time he went to attack I would hold him for about 5 minutes to reassert my dominance. After about a week of that, he went back to being extremely docile. Now he is 24 weeks old and is an extremely behaved rooster. He's very good with the hens, does a good job at protecting them, never attacks, and he isn't attached to me either. It might be I just got lucky, but I'd rather attribute it to my training.
I got 20 straight run EEs and 13 ended up as cockerels. I knew I wanted to keep one, so at about 4/5 weeks old I picked out one to start training as my future rooster. I held him daily, I didn't coddle him, just asserted my dominance frequently. After only a couple weeks of socializing him and not the others, I could tell a big difference. The one I picked out was tame and docile, while the others were aggressive, and they just got worse as they grew older. At only 10 weeks old the other EE cockerels were unbearable, but the one I had chosen was still very well-behaved. I processed the extra roosters and continued holding and socializing the one cockerel. At about 14 weeks old he got a little bit aggressive, but every time he went to attack I would hold him for about 5 minutes to reassert my dominance. After about a week of that, he went back to being extremely docile. Now he is 24 weeks old and is an extremely behaved rooster. He's very good with the hens, does a good job at protecting them, never attacks, and he isn't attached to me either. It might be I just got lucky, but I'd rather attribute it to my training.