The code below filters filenames starting with given substring. It could be changed to fit different needs by working on subfname substring extraction and IF statement:
echo off
rem filter all files not starting with the prefix 'dat'
setlocal enabledelayedexpansion
FOR /R your-folder-fullpath %%F IN (*.*) DO (
set fname=%%~nF
set subfname=!fname:~0,3!
IF NOT "!subfname!" == "dat" echo "%%F"
)
pause