User blog comment:Jopjopjop/Volume 19 Spoilers/@comment-104.7.80.176-20150212012145/@comment-16281343-20150212012824

They are just mass-produced Evil Dragons that changed sides because of Fafnir's shenanigangs.

So it is safe to assume that they don't have special abilities and are the size of what a normal dragon would be (meaning they're big but not too big).

Imo, they already lived their purpose and wouldn't contribute more except for being Asia's guards from grunts as the research done to them highlighted in Volume 18 already bore fruit in Volume 19.