The gods and goddesses throughout The Odyssey use their powers for many different and important roles. Through Odysseus' journey several of the gods play many beneficial roles in order to aid him getting back to his homeland of Ithaca.
The god Zeus seems to have the ultimate power-the power to make the other gods do what he tells them to. A great example of this is seen when Zeus sends Hermes, the messenger god, to tell Calypso that she must release Odysseus and let him return to Ithaca. In order to reach the island of Calypso, Hermes gains the ability of flight by using his winged sandals. Earlier in his journey, Hermes helps Odysseus by using his power of omnipotence to warn Odysseus that Circe has turned his men into pigs. He also uses his intimate and inhuman knowledge of herbs and plants he provides Odysseus with a drug that will save him from Circe's sorcery.
Athena plays an extremely large role in the story as the guardian of Odysseus and uses her powers to help in many times. Athena's most commonly used power is her ability to disguise both herself and others into whatever form she may choose. She begins by appearing to Telemachus several times to help him begin his journey to find news of his father. Athena appears as both Mentes and Mentor to make sure Telemachus goes through with his journey. After his departure Athena even uses her power to give Telemachus a favorable wind to make the journey to Pylos much easier.
Athena also helps Odysseus many times. Again, Athena uses her apparent influence over the wind to make sure that Odysseus is able to reach the land of Phaecia safely. After Poseidon destroys Odysseus' boat on his journey away from the island of Calypso Athena chooses to intervene and calms the winds and the seas. After Odysseus has reached the shore of Phaecia Athena uses her power to make Odysseus appear beautiful even after being on the sea for so many days. This helps Odysseus gain favor with the king's daughter. In order to protect Odysseus from the people of Phaecia, Athena covers the area in a fog so that Odysseus can pass through without trouble.
When Odysseus finally reaches Ithaca Athena offers more help using her godly powers. Again Athena clouds the area in a mist so Odysseus will not be recognized and also to assure that she is the first one Odysseus speaks with. Athena then helps Odysseus hid his treasure, and once again using her power to disguise makes Odysseus appear old, feeble and dressed in rags like a beggar. As Athena had done to Odysseus earlier, Athena chooses to use her power to also make his wife Penelope extremely beautiful. Athena also physically protects Odysseus, such as when she caused an entire volley of the suitor's spears to miss entirely.
During Odysseus's journey throughout The Odyssey all of the gods are not entirely helpful to him. Poseidon is seen as the most destructive of the gods. Because Odysseus blinded his son Polyphemus, Poseidon is using his godly power to make Odysseus's journey as long and miserable as possible. Poseidon destroys the raft Odysseus was using to escape from Calypso's island in a storm. In his last act of fury against Odysseus seen in the poem, Poseidon turns the Phaecian ship which carried Odysseus to Ithaca to stone. Mercifully, he chooses not to bring mountains up around Phaecia as he had originally planned.
Though usually cast in a good light Zeus can also be extremely destructive. After Odysseus' men choose to slaughter and eat the cattle of Helios, even when they are warned specifically not to, Zeus strikes them down. Circe, while not actually a goddess but a nymph , also uses her power in order to change Odysseus' men, and apparently many other men, into pigs.
Throughout the story the gods' powers are also shown to have limits. For example Turisias tells Odysseus that if he were to fall into Charybdis not even Poseidon could save him. Athena also chooses no to help Odysseus many times throughout the epic because of her fear of Poseidon. As mentioned earlier, Circe's sorcery doesn't work on people who have drank a mysterious drug which Hermes gives to Odysseus.
The gods and especially their various powers used throughout The Odyssey drive the story and make Homer's epic far more interesting.