Every year, I make all my grandchildren's costumes. I use plain sweats in bright colors without any logo's on them. Hanes is a good one to use. . .
This costume has always won first place any time I have used it. We usually have someone lead the child around for safety.
When making a costume, I have found the best place to get strange clothes is the Thrift Stores, and also have a husband willing to dress up in anything you buy. Enjoy the picture!