There are some ethical considerations for the gods themselves before the establishment of Zeus's new order discussed in History in the Theogony. Again, Ouranos was the first to do "evil": perhaps it is simply unnatural for a father to entrap his children. Much less, then, is it natural for a father to eat his children as Khronos did. But then it is still unnatural for a son to rebel against his father, as Ouranos proclaimed when he cursed his children and called them "strivers" (titans). Apparently this epithet doesn't apply to the Olympians for rebeling against their father. Perhaps this is because they were themselves victims (maybe it wouldn't have been striving for the Cyclopes and Hecatonshires themselves to revolt). Perhaps this was due to their clemency: Zeus imprisoned his father instead of castrating him, and according to Pindar and Aeschylus, later freed him.
The ethics of the Theogony is based mostly on the world order established by Zeus's accession, however. The will of Zeus is the decider of right and wrong. Zeus is all knowing: even Prometheus can't really get one by him (although "tricked", Zeus actually knew Prometheus's plan with the ox remains: he went along with it, and then punished Prometheus and mankind for it later). Because of his marriage with Themis, and birthing of Dike (justice), he is the lord of justice, and the one who decides what is just.
Next in this series: The Epistemology of Divine Poetry.