The Amulet Coin can be obtained from the player’s mother in Littleroot Town after you win the fifth Gym Badge from Norman. His gym is located at Petalburg City.
If you have Fly then you could simply fly back home and speak to your mom to get the Amulet Coin. If you don’t have Fly then you’ll need to backtrack to Littleroot Town on foot.
Amulet Coin Location
The only prerequisite before obtaining the Amulet Coin from your mother is that you’ll need to beat the fifth Gym Leader.
Gym Leader Norman, who also happens to be your father, runs the Petalburg City Gym. He specializes in Normal-type Pokémon, so be sure to use Fighting-type Pokémon and moves.
When you’ve earned the Balance Badge, exit the Gym, and a short cutscene will play.
After all that, you can now make your way home to Littleroot Town by using Petalburg City’s east exit. By following the path heading east, you’ll eventually end up in Oldale Town.
From here, continue heading south to return to where your journey began, Littleroot Town.
Go inside your house and talk to your mom. After a brief conversation, she should give you the Amulet Coin.
Make sure to let the Pokémon leading your party hold the Amulet Coin, and you’ll be rich in no time!
Amulet Coin Uses + Mechanics
If a Pokémon holding an Amulet Coin participates in a battle, you’ll receive double the amount of prize money after winning that battle. It also doubles the amount of money picked up from using the move Pay Day.
Let your Pokémon hold the Amulet Coin as soon as you get it to increase how much you earn from battles significantly.
Tip: While its effect doesn’t stack with Luck Incense, it does stack with the Prize Money O-Power. Stacking both these effects is the most efficient way of farming money in the game.