Just for a historical perspective:
Pope Youannes XIX (papacy 1929-1942) was the first Pope ever to become Pope from an episcopacy. He was the Metropolitan of Al Beheira (whose successor today is our Locum Tenens).
Pope Macarius III (papacy 1944-1945) was the second Pope ever to become Pope from an episcopacy. He was the Metropolitan of Assuit (whose successor today HE Metropolitan Mikhail turned down the Locum Tenens position, who's a centenarian, and was even ordained before HH Pope Kyrillos VI's papacy).
Pope Yusab II (papacy 1946-1956) was the third Pope ever to become Pope from an episcopacy. He was the Metropolitan of Girga. He was also the first Pope whose Holy Synod decided to remove from his office due to corruption charges. He passed away months later.
The Papacy was vacant for four years, and the papacy was headed by three Metropolitans, one of whom was HE Metropolitan Mikhail of Assuit, who's still alive today.
Pope Kyrillos VI (papacy 1959-1971) was the only Pope in the 20th Century to be ordained
to the Papacy (and thus far, the last Pope to have been ordained to the papacy). He was Fr. Mina el-Baramosy, and was known as a wonder-working monk. Perhaps, the modern golden age of the Coptic Church was started by him. He also began the ordination of "general bishops," for concepts of universal Coptic service, and thus began an era of new ranking among the episcopacy. For the first time, an episcopacy would be considered as separable from the diocese.
He ordained Fr. Antonios el Suriany as "Bishop Shenouda, General Bishop of Christian Education and Dean of the Coptic Orthodox Theological Seminary."
This same Bishop Shenouda would be become Pope Shenouda (1971-2012), and while being the fourth Pope to become so from an episcopacy, he would be the first Pope to become so from being a general bishop, rather than a diocesan one.
A short article about the last 10 Popes posted by Al-Ahram online:http://english.ahram.org.eg/NewsContent/1/64/37154/Egypt/Politics-/The-last--Coptic-orthodox-Popes-.aspx
Ahram Online takes a quick look back at the last ten patriarchs of the Coptic Orthodox Church of Alexandria.
The numbers are off. Of course, Pope Shenouda was the 117th Pope, not the 118th. Everyone before before, subtract one as well.
So in actuality, there are three precedents where diocesan bishops became Popes. Which makes sense, since there were no such thing as "general bishops" before Pope Kyrillos.