Yes. I think so.

You can have a character who is one note as long as they're entertaining to watch and read. I can ignore the one flat character in your cast if the rest are doing a lot of work for the plot.

Lets say you've got three main characters. They all do something for the story however one of them does not have an emotional arc where they change and grow but the other two do. This isn't a bad thing it just means that the other characters have a heavier weight to carry maybe the last one just doesn't go through as much as they do. And that's okay. 

Not everybody goes through a ground-breaking change in the real world either.

If there's a character that's one note that is perfectly okay as long as they contribute.