The ONLY way is to hack the game since you are not able to buy or gain coins other than playing the voltorb game. So all you can do is rely on is your skills with this game to earn a whole lot of coins.
50000 coins in coin case, press [Select] 94000130 FFFB0000 62111880 00000000 B2111880 00000000 10001068 0000270F D2000000 00000000
In Pokemon Yellow, you can obtain the coin case from a man sitting at a table in the cafe in Celadon City. The purpose of the case is to hold coins for use at the Game Corner. In Pokemon Yellow, the Coin Case can hold up to 9,999 coins.
Receive from Mr. Game at the Goldenrod Game Corner.
well you can do it with cheats or by yourself
you buy it in the game corner with coins after you get the coin case
50000 coins in coin case, press [Select] 94000130 FFFB0000 62111880 00000000 B2111880 00000000 10001068 0000270F D2000000 00000000
In Pokemon Yellow, you can obtain the coin case from a man sitting at a table in the cafe in Celadon City. The purpose of the case is to hold coins for use at the Game Corner. In Pokemon Yellow, the Coin Case can hold up to 9,999 coins.
Receive from Mr. Game at the Goldenrod Game Corner.
well you can do it with cheats or by yourself
you buy it in the game corner with coins after you get the coin case
you can get a focus band by winning coins in your coin case then just go buy a focus band with your coins
You can get those at the Rocket casino at Celadon. Talk to the person at the counter.
You can buy Pokemon, though not with the money you buy stuff like potions with. In Goldenrod city and Celadon city there is a game corner, you play a coin game called Voltorb Flip and earn coins. You can buy Pokemon with the coins too. In Goldenrod, you can buy an Abra (200 coins), an Ekans [HeartGold] or a Sandshrew [SoulSilver] (700 coins) and a Dratini (2100 coins). At Celadon, you can buy a Mr. Mime (3333 coins), an Eevee (6666 coins) and a Porygon (9999 coins).
Must be on: 00006FA7 000A 1006F5CC 0007 Infinite coins in coin case: 82002DEC 270F
You can only get one coin case.
put the amulet coin on any Pokemon and you may have more coins
use the amulet coin to dubble prize money