How do you USE the powder jar on Pokemon Leaf Green?

It carries berry powder which can be made using the berry crush machine in the Pokemon center it's located upstairs you must talk to the lady behind the far right counter with a wireless adapter connected she will save your game then you can choose Berry Crush have a friend join you then keep pressing the A button to crush the berries you put in the machine in order to create berry powder. Once you make some you can take them to the old man who gave you the powder to receive rare items from him ranging from Energypowder to PP Up.