Wario Land 4/Item Shop

The Item Shop is the room in the hallway before the Boss Room. You can buy items in a shop by earning Frog Medals in the Mini-Game Shop. The purpose of the items is to lower the health on a boss so that they are easier to beat. Many bosses, except Golden Diva, have exactly one weakness item, which can reduce their health to only two counts. If you choose to buy an item other than smile, Wario and the shop guy will immediately move to boss room and start fighting.

Notice that, the shop in the Entry Passage does not provide the latter four damaging items.