Like many sentai mechas, the main mecha combines with other mechas to form a devastating super mecha or Ultrazord. Gosei Great and Gosei Ground can be combined to form Ground Gosei Great.
Ground Gosei Great Combanation!!
Though Ground Gosei Great is pretty much a part formed mecha, the overall size just makes it impressive in any collection.
And of course, you merge all of them to form Mystic Ground Gosei Great!