Whoever is interested in adding a Polish or other crested breed to their already existing flock of socalled 'normal' breeds needs to be aware that acquiring at least two, even better three is important.
Usually a crested bird like Polish, Silkies or Holland white crested will not be welcomed by a flock of 'normal' breeds which often leads to severe injuries and even death.
Only chickens that have been raised with the mentioned breeds and are accustomed to their unusual looks and behaviour should be kept together.
So, unless your flock is all crested birds you better keep the crested breeds in a separate coop and run.
And please, trim their mostly overgrown head feathers to allow for unobstructed view. Otherwise they might not only have no way to orientate but even starve to death as has happened to a friend of mine with her beloved white Silkie hen.