Great questions, Shades. Wow, what a thinker.
Assume:
c:\a
c:\b
Same computer.
Why 10? That was just a hypothetical. If "batch file" (or .ps1 script) user can put in any number they want. Right?
The key is to pick off 10 folders from c:\a, and move them to c:\b.
(These folder names are hypothetical, too, of course....)
Sweet and simple.