>>43842819I feel that Gen 2 introduced a lot of "round" Pokemon, so Hydreigon would fit in concerning that department. As for popularity, Oh you can bet it'd be among the most popular Gen 2 Pokemon of that time. Hydreigon would have probably been viewed as a rival to Tyranitar, which is fitting considering the latter's allusion to Godzilla.
Dragalge in Gen 1.