Zeus was hidden from Cronos when Mother Earth and Rhea worked together to disguise Zeus as a stone to swallow. From there,Zeus grew up alone, nursed by nymphs and the fairy goat. Soon he was powerful enough to face his father.
I will thank the nymphs with horns of the goat, and make a breastplate with the goat for myself. Now Cronos shall be defeated by me.
Metis, Zeus' first wife helped him by tricking Cronos into eating a herb that let him puke out all of his previously eaten brothers and sisters.
Zeus freed Mother Earth's sons from Tartarus, and they helped them fight bravely in return. They also helped them craft weapons (like Zeus' lighting bolt and Poseidon's trident). The Titans fought a bitter battle, but soon gave up, and Zeus locked them in Tartarus, in the Underworld.