You must speak with Oak’s Aide on the top floor of the gate east of Fuchsia City in order to obtain the Experience Share in FRLG.
Once you have captured at least 50 distinct Pokémon, including Pokémon that you have evolved, he will offer you the experience share.
Head to Fuchsia City and speak with Oak’s Aide to receive your free experience share once you have 50 or more Pokémon caught and displayed in your Pokédex with a small Poké ball icon.
Catching 50 Pokémon is the only requirement for receiving the Exp. Share.
The good news is that the Safari Zone is in Fuchsia City, right next to where you get the Exp. Share.
So, if you haven’t had a lot of opportunities to catch Pokémon at this stage in the game, you can pause there briefly and fill out your Pokédex.
How to reach Fuchsia City?
I’m going to assume that if you have 50 Pokémon that you have previously traveled to Fuchsia City, but just in case, let me explain:
Step 1: From Celadon City, go west until you find Snorlax.
Step 2: Play the Pokéflute to rouse Snorlax, then enter the structure to his left.
Step 3: Ride down Cycling Road after passing through the gate (you must have a bike).
Step 4: Continue riding all the way down Cycling Road, then turn east and enter the gate on Route 18.
You can get your experience shared at Fuchsia City, which is on the other side of this building.
How to get to Professor Oak’s Assistant?
Here is where to find Oak’s Aide and obtain your Exp Share once you have enough Pokémon:
Step 1: get to Fuchsia City and proceed to stroll eastward till you reach Route 15.
Step 2: Enter the security building on Route 15.
Step 3 is to ascend the stairs inside the guardhouse.
Step 4: Interact with Professor Oak’s Assistant, the man in the lab coat.
Step 5: Respond “Yes” when he inquires as to whether you have 50 Pokémon or not.
He will give you the Exp. Share, which you can then offer to any of your Pokémon as a held item if you do have 50 or more Pokémon (I know you aren’t lying).
How does EXP share operate and how do you use it?
Give the Pokemon you want to gain EXP for the EXP Share.
The owner of an EXP Share need not even engage in combat to obtain EXP.
Next, simply use any Pokemon in your group to defeat rival Pokemon in combat.
The Pokemon with the EXP Share will receive 50% of the EXP and stats, and the other 50% will go to the Pokemon engaged in combat.
If there are several Pokemon present during the battle, the EXP shareholder will still receive 50% of the prize money, and the remaining 50% will be distributed among all the Pokemon present.
Assume that the EXP is 200. The Pokemon in the battle will divide the remaining 100 Exp, and the Exp shareholder will receive 100 of them. Both Pokemon would receive 50 if they were engaged in combat.
They receive more EXP if the EXP shareholder initiates the combat and is replaced. In essence, the holder receives 50%, but because they took part in the fight, they will also receive 25% extra from the other 50% and the person who vanquished the foe.