You can use the CrossTab/Table control to generate dynamically columns(you should group by a dynamic group in the crosstab column groups).
If we understand you correctly, you don't need subreports, all you need is a CrossTab inside the Detail Section.
If the crosstab does not fulfill your needs, you can additionally check the following thread: Dynamic Table Columns which elaborates on dynamically building a Table item.
the Telerik team
Have you tried the new visualization options in Telerik Reporting Q1 2013? You can get them from your account.