Prof. Oak's aide will give you the item if you have more than 40 Pokemon at Route 11.
first go to Mr. Pokemon first have the red scale and he will give you it
Talk to Mr.Pokemon after you get a red scale from the red gyarados
# after you defeat or catch the red gyrados you pick up a red scale. # then afteryou get it go to mr pokemons house (the guy who gave you the mystery egg) and he will trade you your red scale for the expshare.
how to get exp.share in pokemon blue
If you give a Pokemon not in battle an Expshare, the half of the experience points will go to that Pokemon. If you're in a double battle, and one of the Pokemon in battle has an Expshare, 3/4 of the experience points will go to it. It's a very useful item for training weak Pokemon.
After you fight the Red Gyarados at Lake Rage, go talk to Mr. Pokemon. He will offer you the EXP share for the Red Scale you get for beating/capturing the Red Gyarados.
go to mr stone
You can get an Exp. Share from the chairman at the Pokemon Fan Club in Iccirus City.
go to the bike path at eterna city
Simple, Give it to one of your weak Pokemon that you want it to be strong.
After catching or killing or running away from the red gyrados it will say u have obtained the red scale. Got to Mr.pokemon house and talk to him and trade it for an exp share. The red scale has no use anyway that i know of
In the Big building to the right of fuchsia city.