First post here, but I wanted to post a warning/glitch with this particular item...
Simply put, you cannot down-level a level 100 pokemon with it. It simply says it would have no effect. Seems the game treats it the same as a Rare Candy.
My issue? I wanted to beat a certain Garchomp that was way above my level right? Well, my Meowth pickup army had gotten me a lot of Rare Candies... I leveled my Gyarados to 100 knowing that it might use ice fang and win me the fight. It did, but to my horror after saving, I could not use the common candy on it...
I'm sadly stuck without my beloved flying water pokemon as it will never listen to me. I know it's my own fault, but I trusted the candies, I trusted them!