If my memory doesn't fail, you get is from the professor's assistant after going down the bike trail to the south.
From a scientist.
An exp share allows you to share exp with another Pokémon. You can get it in Pokémon Diamond Pearl and Platinum near Eterna City.
Once you get 35 Pokemon in your PokeDex, Prof. Rowan's aid will give you the Exp. Share in Eterna City's gatehouse.
you could switch Pokemon in battle then all Pokemon that battled get exp or you could get the exp share and give it to one of your Pokemon
use the exp share
4 all i know each Pokemon trainer games have only one Exp. Share in the whole game
In diamond and pearl it is 35. an it is an EXP SHARE not and esp shard.
In the little building separating Eterna City from Cycling Road, talk to the man in the lab coat. He is Dawn's/Lucas's father. He will ask about your pokedex, and give the exp share.
You can get it from Dawn's/Lucas' father at the building between Eterna City and cycling road.
give the exp share to a weak Pokemon when you use any Pokemon to fight exp goes to the fighting Pokemon and the 1 with the exp share.
Yes, you can get it from Dawn's/Lucas' father at the building between Eterna City and cycling road.
give the Pokemon you want to train an exp share then put your strong Pokemon first on your team and train on high leveled Pokemon the Pokemon with the exp share should level up by itself!