If you go north of Harthome City you will find the Amity Square you can go in if you have a pikachu, clefairy, jigglypuff, driflim, pachirisu, torchic, bunneary, shroomish, psyduck, skitty, or a happini in the front of your party. You will find it hidden in a hut to the left of the boy with the drifloon. (Your Pokemon will come out of its ball.)
You get an amulet coin and keep battling the elite four
elite 4 with amulet coin and pay day
In Red the Amulet Coin item does not exist.
Diamond Amulet becomes an Amulet of Power - It gives some attributes to Attack and Defence bonuses.
You get the amulet coin by bringing a "cute" Pokemon into amity square andgoing to the old ruins. then you go inside the left one and take 2 steps forward then one to the left. Don't move and press A. you should get it.
You can find an Amulet Coin in the Goldenrod Department Store basement.
An oak aide in the big building west of celadon city has amulet coin.
The amulet coin is in castelia city there are 3 dancers (Pokemon trainers) and if you defeat all 3 at the fountain the one in the middle will give you the amulet coin. The trainers have pansage, pansear and panpour.
it increases money gotten from trainer battles (npc trainers)
The amulet coin is in the basement of the pokemart in goldenrod while you defeat the rockets that take over the radio station
The amulet coin is in the Goldenrod Department Store Basement (you get to it through Team Rocket's hideout in the underground path).
The amulet coin is in the east gate of amity square, The Amulet Coin is obtained in Hearthome city's East Entrence of Amity Square (must be east). Enter and go to the third ruin all the way down the straight path you can take and pick up the PokeBall with the Amulet Coin containing it. Hope this helps.