The Maximum amount of coins you can earn 50,000 however you cannot earn this amount in one game alone.
The game itself depends on the multiplier cards you get, and the coins earned in levels 1-5.
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Level 1: 20-50 coins
Level 2: 50-100 coins
Level 3: 100-200 coins
Level 4: 200-500 coins
Level 5: 500-1000 coins
Level 6-8: 1000+ coins
So if you were to earn a minimum of coins you would receive 3870 coins in one game, however levels 6-8 can give you more than a 1000 coins although the maximum is unverified.
Source: DB Answer
Bulbapedia
