Your right, with the card that Bard gives you there is no need for cheats, When I post the request was because I tought to fight the Gambler I have to reach A rank on the card game.
Yeah basically, the Bard card is your best bet against her. You can also beat the old lady a bunch of times to get her cards to make it even easier since hers are mostly monster type cards and wont be affected by the bard card's power down ability