The title “the Great” is one that comes through tradition and not any special naming ceremony. Essentially it means that in history enough people referred to the individual as So-and-So the Great that the name sticks as his or her title. The title is one that comes from the ground up rather than the top down.
As of right now only two Popes are universally referred to as “the Great”: Pope St. Leo I and Pope St. Gregory I. In the current day many have called Pope John Paul II, Pope John Paul the Great. While I fully agree, only time will tell if the title sticks.
