It's all relative to the environment, data source, quality of the data, etc.
If I have to write a supposedly simple report from a database that is poorly written it may take advanced skills to pull it off.
Advanced is also ralative to your experience. A seasoned report developer may be able to complete a report job that a less seasoned report developer will find advanced.
My response to that question is "The answer is relative to the environment, data source, quality of data, documentation on the DB Schema, specification, etc. What do you consider an advanced report?