The figure that killed Angra Mainyu was the Great Other.The narrative mentions Angra freezing to death, and the Others have control over cold.
There will be another champion representing the Great Other.It will be this war's equivalent to Avenger.
There will be another champion representing the Lord of Light.It will be this war's equivalent to Ruler or Shielder.
The Stranger's Champion is Arya Stark.She's a Faceless Man and she uses wolf metaphors a lot. She can also see through an animal's eyes, which Arya can do.
The Mother's Champion is Aegon "The Conqueror" Targeryan.His description matches Aegon's.
The Crone's Champion is either the Three Eyed Crow, Littlefinger, Varys, Tyrion Lannister, or Samwell Tarly.The Champion is supposed to be someone who believes knowledge is power, and these guys are intellectuals or knowledge brokers in some way.