This move effect may be in need of research. Reason:What happens with moves called by Mirror Move, Metronome, Encore, Instruct? (using priority moves at 0 priority, and interaction with non-priority moves used at +1 priority due to these moves being boosted by Prankster) You can discuss this on the talk page.
If an opponent uses a priority move (including moves boosted by Prankster, Gale Wings, or Triage) that targets the Pokémon with Queenly Majesty or its allies, Queenly Majesty prevents the Pokémon from executing that move (PP is still consumed). When this occurs, the text "[Pokémon] cannot use [Move]!" is displayed.
Priority status Z-Moves will have their Z-Power effect activate. For example, if a Pokémon uses Z-Baby-Doll Eyes on a Pokémon under the effect of Queenly Majesty, the user will still gain Defense, but it will not lower the target's Attack.