Theory-1 

 According to my opinion Ogway was given the title of Dragon Warrior by the Universe after the defeat of Kepa (An Ancient Real Dragon Warrior) and he passed his title to Jindiao but unexpectedly Jindiao became Cruel and Greedy to gain control of all the power of Hero's Chi. So, his title was taken by Oogway and was given to Master Po who became the new Dragon Warrior. So, according to Kung fu Panda 4 Po gives his title of Dragon Warrior to Zhen and becomes a Spiritual Leader of the Vally of Peace however Oogway has very great powers and eligibility and is even higher in powers from the Spiritual Leader. So, Oogway is stronger than Po and among all of the cartoon characters made till now because of his unstoppable force. And there were 5 Dragon Warriors made till know.

Ke-Pa


Oogway



Jindiao



Po


Zhen