In the upper right corner of Doctor Masons lab there is a guy who will give you 60 energy cards if you don't have any. You can put all of your energy in decks and then talk to him and you will get the cards. You can do this repeatedly.
On a turn where you would kill the opponent's Pokemon, do so, then draw a prize. At that point, turn off the game, and select continue duel. You will be left at the same point, where you must kill the Pokemon again, but this time, draw another prize. Do this until you've seen all the prizes.
Here are some promo Pokemon cards- Slowpokelvl9:give fire club dude energys Mewlvl8:challenge hall award Mewtwolvl60:challenge hall award Mewtwolvl60:beat psychic club Surfing pikachulvl13:trade with ishihara Surfing pikachulvl13:trade with ishihara Electabuzzlvl20:trade Imakuni?:beat imakuni a #of times Super energy retreival:beat ronald Arcanine:trade