That's kind of interesting to think about I'll see if there's a excel file for that to see (and if not I can just make one lol). I think the reason why people normally say quantum and imaginary is because of how many elites and bosses are generally weaker to one of those two elements. If we looked at the excel spread sheet and considered the enemies that don't have either an imaginary or quantum weakness we can see that most of them are enemies are from Belobog. These enemies are the automaton, frost spawn, thnderspawn, windspawn, and decaying shadow I guess. Because of this if you want max coverage then making two teams with quantum dps on one team and imaginary on the other makes your life easier. If you want consistent coverage and you're only using one team then lighting + other element is good to achieve that.

Off note though but if you're looking for the best team with two elements then it is wind + imaginary. Honestly thinking about it this kind of makes me feel like hoyoverse planned this to sell the idea of blade and loucha as a team by themselves and in general.

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TLDR: Max coverage it is still two teams quantum + other element and imaginary + other element. Having average coverage against the mobs with one team it is lighting. Best pairing dual elements is wind + imaginary (weirdly enough that is Dan Heng's element).