"If an opponent uses a priority move [...] that targets the Pokémon with Queenly Majesty or its allies, Queenly Majesty prevents the Pokémon from executing that move" (source: Bulbapedia). However, on several occasions the enemy was able to use priority moves on her ally (example: Kecleon gang, with Fake Out and Sucker Punch). Queenly Majesty works properly on Tsareena.