Digimon King is a title given to someone of extreme skill and power. (under construction)
The twelve contestants compete in the Digimon Grandprix to obtain the title of "King of Digimon". Everyone except PicoDevimon wins, as they all crossed the finish line by riding on Agumon's Taiti-Special.
The title is awarded to those who rank the highest in the D-1 card tournament. Makino Ruki is frequently called the Digimon Queen.
Digimon King is the highest rank a Tamer can achieve.
Shoutmon aspires to be the Digimon King in order to protect his village. It is currently unknown exactly what the title entails, however, it requires collecting all the Code Crowns. Aonuma Kiriha also wishes to obtain the title, showing that a human being can also become the Digimon King.
As of Digimon Xros Wars: The Young Hunters Who Leapt Through Time, Shoutmon has become the Digimon King.
In Shoutmon's story he enters the Digital Monster Evolution Tournament in an attempt to become the Digimon King. In Impmon's story and Dorulumon's story, Shoutmon is already the Digimon King and is considered as one of the Legendary Digimon who once saved the world, becoming target of the evil virus.