I noticed that Farigiraf can underspeed Amoonguss at -2 stages if both Pokemon are minimum speed. Using Scary Face from a Pokemon with the Prankster ability on my Farigiraf can allow for a powerful super effective attack on Amoonguss, but Armor Tail might cause a problem if the wording for the ability and the coding don't match up.
None of the priority-blocking effects (Armor Tail, Dazzling, Queenly Majesty, Psychic Terrain, Dark type vs. Prankster) block moves used by a Pokemon against its own teammate.