Can you post some more pictures? Its hard to see that one as it posted so small!
The white ones are most likely pekins. The easiest way to sex them is the quack. When you pick them up, females will have a loud "quack" while males will be quieter and more raspy sounding. The males will also have a curly feather at the base of their tail. But if they are molting or near molt then the males may not have that curly feather.
The black one looks like it may be a cayuga.
I want to say the other two are welsh harlequins, females, but it's hard to tell for sure with the picture. See if you can post some more