Board Thread:Question and Answer/@comment-31892692-20170501223113/@comment-16682378-20170501224252

It's for Elemental Hall teams. So you can make 4 different sets of teams thus you don't need to alter the teams every day, since the EH element switches daily & cards of that element have extra protection as well as Atk & def buff.

Other than that there is nothing to it (you can use your Passion teams on Cool days, the Cool cards in the Passion deck still get the perks).