During the years of the Imperial era, Gokus served as the king of Alzar. When C-3PO and R2-D2 arrived on Sooma as diplomatic couriers, his son was on the planet without Gokus realizing. The king threatened Zornog that if his son doesn't return safe, he would open war on the planet. C-3PO and R2-D2 proposed to bring the Prince back home, but on the way they were attacked by General Sludd and his forces. The droids and the prince managed to reach Alzar in time.
However, when they landed, King Gokus had C-3PO and R2-D2 arrested, believing that they were the ones that kidnapped his son. Plooz defended his new friends and revealed the truth that Sludd was the culprit.