I don't think either would be at all out of place in a show, especially if you are talking about a local show. They have nice lacing - better than I have seen in some show pens! Both of them could be a bit curvier in the backs - that is, their backs are a bit flat. They could be a bit 'rounder' overall. With Wyandottes, you want to imagine a circle, and if you also imagine the bird seen from the side, the bird should fit within that circle. The rooster's legs could be a bit more yellow.
But none of that would stop me putting them in a show. Poultry clubs love to see younger people and kids putting their birds in, because they are the future of showing poultry. You will probably find that your son will get a lot of encouragement. He should talk to the judge after the judging is all completed to get feedback on his birds. Judges are usually more than happy to do that, especially with kids. Often there are junior categories to enter birds into, and junior awards.
Your son can do a bit of research on how to prepare his birds for the show, to have them at their best. As a minimum, clean and scrubbed legs and clean faces and combs are important.
I'd say go for it!!