We were asked to divide the elements into four groups. Criteria: All trios had to work. All three duos in each trio had to work. All three elements in one trio had to be opposite the elements in another. These were the decks (and elements) I came up with:
7gk 7gk 7gk 7gk 7gk 7gk 7gk 7gk 7gk 7h0 7h0 7h0 7h0 7h0 7jo 7jo 7jo 7jo 7jo 7k1 7k1 7k1 7k1 7k1 7k1 7n2 7n2 7n2 7n2 7n2
778 778 778 778 778 77j 77j 77j 77j 77j 77j 7dm 7dm 7dm 7dm 7dm 7t4 7t4 7t4 7t4 7t4 7t5 7t5 7t6 7t6 7t6 7t6 7t6 7t6 7ta
6ts 6ts 6ts 6ts 6ts 6ts 6ts 6tu 6tu 6tu 6tu 6tu 6tu 6u6 6u6 6u6 6u6 808 808 808 808 808 808 808 808 80b 80b 80b 80b 80b
710 710 710 710 710 710 717 717 71d 71d 7q0 7q0 7q0 7q0 7q0 7q0 7q0 7q0 7q0 7q0 7q0 7q0 7q8 7q8 7qc 7qc 7qc 7qc 7qc 7qc
Some decks are untested, and none are perfect. This is just proof of concept. Pick two of any three elements in these decks, those decks duo well together (well.... dark+fire gets a maybe)