Like the Mahābhārata has several explicit references to various incarnations of Lord Vishnu, including that of Shri Rāma, What about the Rāmāyaṇa?
Which all incarnations of the Lord, have been mentioned either explicitly or implicitly in the Rāmāyaṇa?
One may also derive their answers from the other popular versions of the Rāmāyaṇas - Adbhuta, Ānanda, Adhyātma, et al.