I'm not sure if this exists under a different name. Essentially this is a similar category as predator/prey relations. The theme of type advantage involves one character having an inherent advantage over the other due to their elemental type. For example: a water type would find it easy to dominate a fire type. This concept is particularly applicable to Pokemon and related things, but it's a common theme in many magic systems. Suffice to say, I very much like the idea of being able to search for this and see those cute fairies putting the big dragons in their place.