Are there quotes showing Odysseus' intelligence besides when he gives the Cyclops wine or disguises himself to test everyone's loyalty?
When Odysseus finally reveals his identity to King Alcinous of Phaeacia, he says, "I am Odysseus, son of Laertes, who for all craft am noted among men, and my renown reaches to heaven." In other words, then, Odysseus knows that his craftiness and cunning are a big part of his identity, so much so that he references them in his own introduction.
After the crew's tragic encounter with the Ciconians at Ismarus, Odysseus does not send all his men ashore the next time they land somewhere. He lost six men from each ship at Ismarus and is intelligent enough to know that another such loss would be devastating to his fleet. Therefore, he "select[s] two" sailors and "a herald as a third" to go ashore in the Land of the Lotus-Eaters. This way, he cannot lose more than three men.
Later, when he and a handful of his men are trapped in Polyphemus's cave, Odysseus cleverly tells the Cyclops that his name is "No man" or "Nobody" (depending on your translation). Then, when the monster cries for help after Odysseus and crew have blinded him, he tells the other Cyclops that "No man is murdering [him] by craft." His peers figure that no one is hurting him and whatever ailment he has comes from Zeus, so they leave him to pray to his father, Poseidon. In this way, Odysseus wounds the Cyclops enough that he will have the advantage over the monster, but he also leaves the monster's strength intact so that Polyphemus can roll the stone away from the door (and the men will not be trapped behind it). Even Polyphemus recognizes Odysseus's craftiness and intelligence.
Good job in identifying one of the things that separates Odysseus from other heroes in Greek mythology (e.g., Hercules). It's not that he isn't strong; it's that he has brains and brawn. Homer announces it in the opening line of the poem: "Sing to me of the man, Muse, the man of twists and turns" (I, 1; Fagles trans.). You might also note in your essay that the reason Athena likes Odysseus so much is particularly because of his cleverness. When she meets up with him in Ithaca in book 13, she states: "'Always the same, your wary turn of mind,' / Athena exclaimed, her glances flashing warmly. / 'That's why I can't forsake you in your troubles'"(XIII, 374-376). What I find so delightful about the Odyssey is that Odysseus has to rely on his wits to get him out of trouble almost as often as anything else; it makes him more human than a Perseus, for example.
Odysseus creates a plan that will save his men from the Sirens. He has his crew put wax in their ears so that they cannot hear the Sirens.
Next, Odysseus has his crew tie him to the mast of the ship. His ears are not plugged with wax. He can hear the Sirens but cannot give in to their luring because he is tied to the mast.
In this, Odysseus proves his intelligence. He was witty and clever.
Also, another instance in the epic that proves his intelligence is when he was on Calypso's Island. He does not tell her he misses his wife because she will be jealous and not help him get home. Instead, he pleads with her that he is homesick for his homeland. He realizes that she will be more willing to help him if he is only homesick and not missing his wife. He is very wise in concealing the truth form Calypso.