User blog comment:Kogath/Monster Hunter XX Discussion/@comment-33581177-20170327234351/@comment-27465049-20170328133616

I'm pretty sure Uka was a high-rank monster in MHP3rd.

From the Monster Roster in MHGen, I'm guessing they put monsters like Uka and Ala in High-rank because, MHGen being not the main 4th gen game, they initially thought MHGen(X) was gonna be the final of the 4th gen. However, due to it's success and high demand for a sequel, XX was introduced.