I would add Jamie and the hound if Arya is fighting with either one. My theory is if either Jamie or The Hound die, Arya will remove their face and then kill Cersei and/or the mountain. Also, if this is done I done think anyone else will witness. Arya will surprise everyone when the mountain falls.

By the way, why does no one know Arya wiped out the Freys? She did remove Waldo’s face after killing everyone and tell the servant girl “the north remember”