I'm not sure about simple but here is something that appears to work. It has nested directory iterators to locate subdirectories two levels down from the start point.
Top tip: It's always a good idea to prefix any potentially harmful commands with ECHO during testing.
ECHO COPY src dest
to see what would be copied without actually doing it.
ECHO Process files two directory levels down from the start point
ECHO Start point is %CD%
ECHO Searching for files matching %FILESPEC%
REM enumerate LEVEL_2 directories
FOR /D %%A IN (%LEVEL_1%\*) DO (
REM enumerate LEVEL_3 directories
FOR /D %%B IN (%%A\*) DO (
REM Show directory if it contains matching files
IF EXIST %FILESPEC% (
ECHO LEVEL_3 %%B
REM enumerate matching files in the LEVEL_3 subdirectory
FOR %%F IN (%FILESPEC%) DO (
REM ~nx modifier to get name and extension only
REM ~dp modifier to get drive and path only
ECHO COPY "%%~nxF" "%%~dpF.."