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Increases the power of moves used consecutively by 20% each time it is used, up to a maximum of 5 turns (100%). If the holder switches out or uses another move, the boosts are lost. Metronome will not power up individual hits of multi-hit moves (such as Rock Blast) unless they are used consecutively.
Metronome isn't a good item. In competitive battling, Pokemon switch frequently, so gaining boosts will be hard. In addition, using one move repeatedly will put you at a disadvantage. Not to mention that even if you use the same move for four turns in a row, you only obtain the same power as a Choice Band or Choice Specs—in fact, even if you used the same move six turns in a row, you would have done exactly the same amount of damage had you had the Choice item to begin with.
Wild Kricketune (5%).
Dream World (Windswept Sky - requires 7,500 points).