@echo off
Setlocal EnableDelayedExpansion

SET ROOT_FOLDER=C:TEST 1
SET TARGET_FOLDER=C:TEST 2

FOR /D %%G IN ("%ROOT_FOLDER%"*) do (
CD %%G
    FOR /f %%A in ('dir ^| find "File(s)"') do (
        set cnt=%%A
        Echo %%G  : !cnt!
        IF !cnt! == 1 (
            move /-y "*.*" "%TARGET_FOLDER%"
        )
    )
)