The only roo I see is the Light Brahma.
Leghorns do have bigger combs than other breeds at that age and can look gangly.
If your Dark Brahma is a bantam it will be ok because they are being raised all together.
Mine is from Ideal also and it is smaller than all my other standard size chicks. If fact I have a couple larger bantams that are the same age and just slightly smaller than the Welsummer. In my experience, and I have...
Could you give us full body shots besides the just the combs? It helps to see the body shape, feathering and stance.
Also some of your breeds may not be what you think.
It that your coop in your...
Chicks 1, 2, and 3 all have red combs now. My only hope for a pullet is chick 4.
Can anyone tell by the coloring if chick 4 is a pullet?
Also, is chick 3 a Blue Wheaten?
It does look splash but when I checked the Splash OEGB chicks on Ideals site it looks nothing like them.
Most of what I got in my assortment were OEGB. It is getting more "splashing" as the feathers are coming in.