What skill sets (technical and communication wise) do you expect in beginner, intermediate, expert level web developers? What are the factors that has to be considered? Listing down the requirements for these 3 levels will help. Languages and Frameworks are immaterial but the understanding or ability to get things done should be counted as skill/Knowledge e.g. Understanding HTTP Request/Response cycle is a requirement for beginners. Something along these lines-

Beginner-

Should know XYZ.

Intermediate-

Should have understanding of ABC.

Expert-

Should know JKL.