Some of the firmware versions do have G2/G3 in them but not all. http://smoothieware.org/supported-g-codes http://smoothieware.org/supported-g-codes I assume

Some of the firmware versions do have G2/G3 in them but not all. http://smoothieware.org/supported-g-codes http://smoothieware.org/supported-g-codes I assume most of the modern ones do but some of the older 3d printing firmware use a very butchered version of the gcode "standard" which eliminate or rename many of the unused codes.