May an excused person lead a congregational prayer?
A person who is excused in terms of ablution may lead a congregation consisting of people who are also excused like him. However, this person cannot lead a congregation of unexcused people. Because the condition of an imam should not be lower than that of the congregation (Marghinani, al-Hidayah, I, 374,375; Ibn Qudamah, al-Mughni, III, 11 ff.). According to the Shafi’i school, unexcused people may follow an excused person in prayer (Shirbini, Mughni al-muhtaj, I, 367).
Source: Presidency Of Religious Affairs The Turkey, High Board of Religious Affairs FATWAS