Where do you get the experience share in Pokemon HeartGold?

Answer 1

mr.pokemons house,y'know,he gives that togepi egg...fight red gyarados and capture him(not sure if defeating works).you get red scale,with that he trade/transform/produce with/into/to create a exp share!See you meheheheheh!
Take the Red Scale you get from the Red Gyarados and give it to Mr. Pokemon, north of Cherrygrove Town
in Pokemon's House talk to him and trade the Red scale (this is how my brother got it but it didn't work for me) he'll give you it if this doesn't work then get it from a different game.
In Heartgold and SoulSilver you get the exp by giving Mr. Pokemon a red scale that you earned by beating/catching the red Gyarados.
Trade the red scale to mr Pokemon and he gives you the exp share
Defeat or catch the red garados at lake rage. You should then get a red scale. If you go to mr pokemons house and talk to him he should say something about the red scale and then give you an experience share.