You can find the Exp. Share in Rustboro City or in the Lilycove Dept. Store.
Simple, Give it to one of your weak Pokemon that you want it to be strong.
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.
go to mr stone
You can get an Exp. Share from the chairman at the Pokemon Fan Club in Iccirus City.
first go to Mr. Pokemon first have the red scale and he will give you it
go to the bike path at eterna city
In the Big building to the right of fuchsia city.
In Castelia city.. Is in one of the buildings last floor
Prof. Oak's aide will give you the item if you have more than 40 Pokemon at Route 11.
Pokemon Ruby has Pokemon that Pokemon Sapphire does not and Pokemon Sapphire has Pokemon that Pokemon Ruby does not.
Talk to Mr.Pokemon after you get a red scale from the red gyarados