>>58166626
Before gen 8 and 9 I would say the fairy type but In those gens gamefreak finally started making more fairy types based on myths, youkai, and fairy tales which is what they should have always been. Personally I think what makes a ground type a ground type Is way worse off for what makes them the type than fire. However the most boring type with no question is flying. There has never been anything Interesting done with the type.