Ok that hulking monster breaks free from the 12s power, Now this was an impressive feat beating 12 gods with just your own.

This tells me that this thing is of "Godly" level it self. and from basic FF lore Bahamut is commonly know as the King or the Wyrms.

Shinryu on the other hand is God of the Dragons.

And in FF Dissidia which can hear with a conversation with Ultemicia she says the Shinryu is the Dragon God that destroys the world and makes it anew to restart the cycle. Which can easily work its way into there reoccurring umbral eras.