Defense and Special Attack Berries
Travel to Route 123, located in the Hoenn region of "Emerald." It is east of Mauville City and southwest of Lilycove City. In a fenced-in garden beside a house along this Route, search the lower right plant to find Qualot berries, which reduce defense effort values. In the same area, search the bottom middle plant to find Grepa berries, which lower special defense effort values.
Attack and Special Attack Berries
Travel to Route 115 in the Hoenn region, located north of Rustboro City. Among the trees, you will find a row of three pink flowers. Search the middle flower to find Kelpsy berries, which lower attack effort values. Travel to Route 119 in the Hoenn region, located northeast of Mauville City and southwest of Lilycove City. Along the route, you will find two plants resting side-by-side in a patch of dirt. Search the plants to find Honew berries, which lower special attack effort values.
HP and Speed Berries
Travel to either Route 119 or 123. On Route 123, the HP berry, Pomeg, can be found in the same location where the player found the defense and special defense berries. Search the bottom left plant in the fenced-in garden to find the Pomeg berries. Along Route 119, search the three mushroom-like plants in a dirt patch to find Pomeg berries. Travel to Sootopolis City, located southwest of Mossdeep City and southeast of Lilycove City. Speak to Kiri to get the Tamato Berry, which reduces speed effort values.
How Berries Work
If a Pokemon's effort values in that particular stat are more than 100, the first berry will reduce the stat to 100. Afterward, each berry will reduce the effort value in that stat by 10 points. This will enable the player to increase stats in other areas. In Pokemon games besides "Emerald," berries can be used to make creations called "Pokeblocks." However, these are permanent means to raise effort values.