I looked at your Skarmory, and it is a legal Pokemon with valid trash bytes.
Trash bytes are bytes that no one knew what they were for until later. As for where to find trash bytes, they are the hidden hex values in Pokésav (upper right), but if you use Pokegen, you shouldn't have to deal with them.
If you do use Pokesav, then you can look here for a guide explaining what they mean.