The EXP Share is a very special hold item that allows players to have one of their Pokemon gain Experience even when they aren't put into battle. The EXP Share aids players in raising lower leveled Pokemon very quickly - such as Magikarp so it can Evolve into Gyarados - or by helping them keep their entire Pokemon Team around the same levels. Unfortunately, the EXP Share is very difficult to obtain. In order to do so, you must first catch fifty different Pokemon Species. After you do, you can obtain the EXP Share from Professor Oak's Aide found within the gate that connects Fuchsia City to Route 15.