According to Official Nintendo Magazine, the English-language versions of Heart Gold and Soul Silver have had their gambling devices replaced by a new mini-game which, according to the magazine, is surprisingly fun.
In the new game, players must flip over panels in a five-by-five grid. Some panels hide multipliers for the player's coins. Some, however, hide Voltorbs, which end the round and cause the player to lose all coins accumulated to that point. You can guess where each Voltorb is hidden using numerical clues at the end of each row and column -- it other words, its Picross meets Minesweeper. Meets Pokémon. Yes, please.