My girls showed chickens for maybe 7 years each in 4H (this is my youngest's 10th yr), and of course every county and judge is different. You never know what a particular judge is going to think is important. At our fair, you can show a pullet, a hen, a rooster, a cockerel, and you can show 6 eggs. You could show all of them, or just a pullet if you wanted. But not 2 pullets, or 2 roosters. The rules will be in the handbook they give you at the county extension office, I'm sure all fairs are different.
If you mean the chicken has the wrong type of comb, like a rose comb instead of a single comb, then that would be a major fault for a breed. In our experience, the chickens are judged as a representative of their breed. So pick one that represents its breed best...right comb, right color legs (like yellow or slate or whatever), no cross beaks, right color, etc.
Also, showmanship was a big thing. Study up on the breed you are showing, anatomy of the chicken, what color egg does it lay, what do you feed it, etc. The judge will ask them individually different questions. Showmanship also includes how well you prepared your bird for the show. Clean their faces and legs, take a nail brush to their toenails. My oldest use to dab a teeny tiny bit of vaseline on their legs and beak right before the show. They'd look all shiny and pretty. People looked at her weird, but she won showmanship several times.
The first chickens my girls showed was a naked neck and a brown leghorn. I don't remember the rest! Main thing, they had fun, learned to help others, and be more responsible! and it got them into the bigger animals...sheep, pigs... Good luck!
