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When Magic Room is activated, held items cease to have an effect for the move's duration. Using Magic Room while the effects are already active will cause the effects to cease. All Pokemon on the field are affected by these effects, even in doubles and triples. This move has a priority of -7. If a Pokemon with Prankster uses Magic Room, this move has a priority of -6. Under Magic Room, Natural Gift and Fling will fail if used, but the exchange of items (eg. through Thief or Trick) will still be possible. Berries can still be consumed through Pluck or Bug Bite. If a Pokemon has a Choice item, they can switch between attacks while Magic Room is active, but once the effect ceases, they will be re-locked on whatever move they were locked on before Magic Room was used. If this move is used during the effect, the effect ends.
Magic Room has little competitive use. It is outclassed by Embargo, which does not affect the user. Furthermore, preventing items effects is not a powerful strategy, since most items are not central to a strategy.
Embargo is another move that prevent item use, though it only affects the target until the target switches out.