Junkers will out-maneuver the B-25 but it will still be a draw. JU-88 does not have enough forward firing rifle-calibre ammo to bring down a B-25.
EDIT/If the Ju-88A-4 would have the 20mm MG-FF/M option, it would be a different story...but even then the 60 round drum would require very accurate gunnery./EDIT