I'm not too good on pony critique but I'll try.
Rowdy looks as though he has a nice expression and a kind eye. He seems to be a stocky boy, but everything pretty much looks in proportion with one another, although in the first picture his neck seems to be a little too short but I think it's just the angle of the photo. His back is also slightly long but nothing major.
**EDIT** I just noticed that in the first & second pictures he also looks slightly sickle hocked.
Shadow: First of all, he looks like he also has a kind eye and nice nature. He looks pretty much in proportion overall, but the one thing I did notice was his forelegs. One last thing, at the knee he seems to be what is commonly called "under at the knee". This is when the tendon is flexed to far back, creating the look that the horses knee is somewhat "tucked in". I wouldn't worry about it considering his age.
Prince: The first thing I noticed about him is his hocks. They look really well proportioned. He seems to be camped under in the forelegs in both pictures, although this could be just from the way he happened to be standing.
Sonny: He seems to be basically in proportion, although there a a few little things that might be an issue if he were a bigger horse. He is a cutie, and from what I can see has some of the flaws that any typical pony could have, so I wouldn't worry to much about it.
These pictures weren't the best to critique, but I got what I could from them. I think that your horses are absolutley gorgeous!