Has an AFL game ever ended 25-20?
Exactly once. On June 30, 1906, Fitzroy beat St Kilda 25-20, and no AFL game before or since has ended that way. When it happened it was a scorigami, the first 25-20 in league history.
That makes 25-20 the 3836th most common final score out of 6,607 that have ever occurred in AFL. One point away, 26-20 has happened never and 25-21 has happened never.