Edo gave us some great information on the Lucky Stadium cards.  "The “Lucky Stadium” Promotional card was given out at special tournaments in Japan.  The most unique aspect of this card is that eight (8) different versions of the card exist—one for each of the regions that the tournaments were held in.  The effects of each of the eight cards are the same; the only thing that is different between the cards is the picture (for instance, the Tokyo one has the Tokyo Tower in the background):

“Once during each player’s turn (before his or her attack), that player may flip a coin.  If heads, that player draws a card.” Since it is a Stadium card, it also follows standard stadium rules." - Thanks Edo!!!