T. A. Rodgers
I don’t think any character should be completely flat. Why identify a character if they have no dimension? I understand a crowd of people may not have character traits, but a main antagonist? Surely, you want the reader to invest their time with your main characters. This includes the antagonist. Some of the best novels I have read had a incredible antagonist full of character traits and flaws. If you are going to spend time with your characters make them fun and exciting. Give the reader something to remember.