In Ramavatar, Adisesha took the avatar of Lakshmana. In Krishnavatar, he incarnated as Balarama. After that, Adisesha took the avatar of Ramanujacharya to spread the Vaishnavism. It is also believed that Raghavendra is Adisesha's avatar. Likewise, is there any puranic reference for Adishesha's avatar at end of Kaliyuga to accompany Narayana as Kalki who will come on a white horse with sword?
In this you will find:- it is written in Kalki Purana that he will have four brothers who are Sumanta, Prajna and Kavi.