YES...Very easily
the lowest speed stat a lv.100 munchlax can have is 13
and with -6speed, 13/4=3.25, rounded to 3
though I can't find the maximum speed lv.1 ninjask has, most lv.1 Pokemon will have more than 3speed stat
EDIT-
Actually, any Pokemon with 6stage speed will have more than 3 points, so
ANY Pokemon with that option, even lv.1 munchlax, will outspeed that munchlax,
without even having to need good nature, item, ev or iv
