Zeus was the king of a village in Kanto. Per the traditions of the village, a competition was held to find a new king. The person who possessed the crown by sundown will be crowned the new king. At the end of the day, Hank was holding the crown and thus named as the king.
Zeus was not seen much throughout the course of the episode and so little was known about him. However, he seemed quite eccentric for thinking it would be acceptable to have an Aipom for a king.