it is a Myth that Lord Rama was not discussed in Mahbharta,infact his Viswaroopa was discussed in mahabhartha just like it was discussed in Yudhakanda 117th sarga of Valmiki ramayana
Ramayana is discussed 4–5 times in Mahbaharata
- Vana Parva, Tirtha Yatra Parva section CXLVI
- Vana Parva, Draupdi Harana Parva section CCLXXIV
- Shanti Parva, Moksha Dharma Parva section CCCLX
- Vana Parva Tirtha Yatra Parva Section XCIX.
- Anusasana Parva: Anusasanika Parva Section CXLIX
- Vana Parva, Tirtha Yatra Parva section CXLVI
And it came to pass that the mighty son of Dasaratha the heroic Rama, who is Vishnu himself in the form of a human being, took his birth in this world. And in company with his queen and brother, taking his bow, that foremost of bowmen with the view of compassing his father's welfare, began to reside in the Dandaka forest.
- Vana Parva, Draupdi Harana Parva section CCLXXIV
I have already ordained that which is needful for that purpose. Indeed his death is near! Urged by me, the four-headed God hath already been incarnate for that object. Vishnu, that foremost of smiters will achieve that object!' "Markandeya continued, 'Then the Grandsire also asked Sakra, in their presence, 'Be thou, with all the celestials, born on earth! And beget ye on monkeys and bears, heroic sons possessed of great strength and capable of assuming any form at will as allies of Vishnu!'
- Shanti Parva, Moksha Dharma Parva section CCCLX
At the conjunction of treta and dvapara, I will be born as King Rama, the son of Dasharatha. Because of the injury that they caused to Trita, the two rishis who are the sons of Prajapati, Ekata and Dvita, will become malformed and will be born as monkeys. Born in those forms, those noble ones will be residents of the forest.
Appearing in the forms of a swan, a tortoise, a fish, O foremost of regenerate ones, I shall then display myself as a boar, then as a Man-lion (Nrisingha), then as a dwarf, then as Rama of Bhrigu's race, then as Rama, the son of Dasaratha, then as Krishna the scion of the Sattwata race, and lastly as Kalki. When the auditions in the Vedas disappeared from the world, I brought them back. The Vedas with the auditions in them, were re-created by me in the Krita age.
- Vana Parva Tirtha Yatra Parva Section XCIX.
And shot by the hand of Rama, that shalt, confounding by its energy the other Rama, came back blazing into Rama's hands. And Bhargava, who had thus been deprived of his senses, regaining consciousness and life, bowed unto Rama who was Vishnu. And commanded by Vishnu, he proceeded to the mountains of Mahendra.
"Lomasa said, 'Listen, O king, to the history of Rama (the son of Dasaratha) and Rama of Bhrigu's line gifted with intelligence. For the destruction of Ravana, O king, Vishnu, in his own body, took his birth as the son of illustrious Dasaratha. We saw in Ayodhya that son of Dasaratha after he had been born. Even this O child, was what befell Rama of spotless deeds in days in of yore, after he had, O king, met Vishnu (in the form of Dasaratha's son)!'"
“Behold me now in my native form: I give thee sight.' Then Rama of Bhrigu's race beheld in the body of Dasaratha's son the Adityas with the Vasus, the Rudras, the Sadhyas with the Marutas, the Pitris, Hutasana, the stellar constellations and the planets, the Gandharvas, the Rakshasas, the Yakshas, the Rivers, the tirthas, those eternal Rishis identified with Brahma and called the Valkhilyas, the celestial Rishis, the Seas and Mountains, the Vedas with the Upanishads and Vashats and the sacrifices, the Samans in their living form, the Science of weapons, O Bharata, and the Clouds with rain and lightning, O Yudhishthira! And the illustrious Vishnu then shot that shaft. And at this the earth was filled with sounds of thunder, and burning meteors”
And living disguised in the abode of Dasaratha, Vishnu of dreadful deeds slew the Ten-necked one in battle.' Thus remaining in disguise in various places, high-souled persons have before this conquered their enemies in battle. Thus cheered by these words of Dhaumya, the virtuous Yudhishthira, relying on his own wisdom and also that acquired from the scriptures regained his composure.
- Anusasana Parva: Anusasanika Parva Section CXLIX
He that himself enjoys and endures the fruits of all acts, (or, He that assumed the form of Rama, the son of Dasaratha, and going into exile at the command of His sire made a treaty with Sugriva the chief of the Apes for aiding him in the recovery of his kingdom from the grasp of his elder brother Vali in return for the assistance which Sugriva promised Him for recovering from Ravana His wife Sita who had been ravished by that Rakshasa and borne away to his island home in Lanka),
He that enjoys and endures (weal and woe, in the form of Jiva); He that assumed the form of a vast Boar; (or, He that, in the form of Rama, was the Lord of a large monkey host); He whose vision extends in all directions: He that has no Master; He that at all times transcends all changes; He that (in the form of Rama) had to lie down on that bare ground; He that adorns the earth (by His incarnations);He that is armed with the bow (in the form of Rama); He that is conversant with the science of arms;