User blog comment:Kogath/Monster Hunter XX Discussion/@comment-6050823-20170505143130

Some more info was recently revealed about some things both lore wise and development wise.

Development
 * According to the developers of the Monster Hunter series, there are three elements that they use to make a Flagship Monster. These three elements are a coolness that attracts the players, a newness/originality not found in other monsters, and power other than various attacks.
 * Barufaruku's design motif was hawks and falcons.
 * Occasionally, they have public workshops where fans make up a new monster that uses a certain behavior for survival.

Ecology
 * When Massacre Demon Diablos enters its Massacre Charging State, it is known to produce body fluids in order to cool itself. While enraged, a Diablos's body heat increases drastically. It is said that Massacre Demon Diablos's body temperature is major higher than one would expect.
 * Lao-Shan Lung can be as old as a thousand years old.
 * Massacre Demon Diablos is legendary. It has been described in many legends in the Desert, going as far back as ancient times. When this devil encountered anything, it would be driven into maddening rage, once it got a foe in its sights.
 * This Diablos has caused many hunters to retire, including Lavanda and Wehner. It has also killed many hunters, soldiers, etc. over the past few decades.
 * Massacre Demon Diablos got the secondary name, Massacre Demon, due to its aggressive nature and from it being considered a devil or a demon.
 * Silver Ridge Gammoth could be considered to be an old Gammoth.

Sources
 * Monster Hunter XX
 * https://www.inside-games.jp/article/2017/04/27/106843.html
 * http://nindori.com/books/index.html