Personally, I've had more fun with Voltorb Flip than with any of the slot games. Playing it reminds me of Sudoku, and I've managed to narrow down to the higher numbered cards in later games. I've had some surprising moments, as well as some heart-breaker ones too, but still, MORE FUN. Addictively more fun than slots.
Finally made it to Lv. 6 or 7.... and earned up enough coins for my female Dratini~ YAY. Now I'm down to 35 coins... so time for more playing (instead of training? Of course!)!