If you already got 3 medals on Ultimate map and just want to farm it for stones (aka chests) it seems that best way is to keep 1 squad on each of two top most start nodes (there are squads there by default) and move 2 teams to helper bottom start node. This assumes each of top teams can fight and survive at least one pest (50k power per those squads seems to be enough), and 2 of 3 bottom squads will be strong enough to go through small pests and 2 bosses to the finish flag (a 70k power squad seems to be enough to solo it thou so you could improvise a bit).