§1. To become a pastor validly, one must be in the sacred order of the presbyterate.
§2. Moreover, he is to be outstanding in sound doctrine and integrity of morals and endowed with zeal for souls and other virtues; he is also to possess those qualities which are required by universal or particular law to care for the parish in question.
§3. For the office of pastor to be conferred on someone, his suitability must be clearly evident by some means determined by the diocesan bishop, even by means of an examination.
Source: Code of Canon Law (Vatican.va)