I figured out how to outsmart the game. They won't let you transfer cards from 2 of the same saved game, even if you save into another slot. This is the ONLY way you can get more than one of Demon Swordsman, The Emperor, Ice Skeleton, God of Destruction, Doppleganger, and all those other un-duplicatable cards. I get unclear in explanations, so heres a simplified step by step explanation: 1. Create a new game. 2. Get to the point where you're ready to battle Katia. Do NOT battle her. 3. Save. 4. Kick her butt, and take cards from LK1. 5. Save onto another profile. Do NOT save on the same profile as this game (so this game won't have her beat yet, and you can take her cards again) 6. Transfer all the cards from that game to another using 2-Player mode. You can't transfer them between the 2 games you created for this whole ordeal. 7. For extra cards, transfer your cards from you're game that you want to transfer TO to the game that hasn't beaten Katia. That way, every time you save after beating Katia, you get an extra of that card.
How to get some of the harder cards to get in-game
Added 8 May 2013, ID #9519
Jack-o-Lantern: Gotta d-load it from LK1.
Pazuzu: Capture in Proving Grounds, or catch in 2-Player mode
The Emperor: I can't figure out how to get any stars in the last level of the Proving Grounds, but he can be captured. Use 2 great turtles because they deal some damage and are a PAIN to kill, even with the emperor.
Capture card: gotta buy in Bashea. Theres a guy behind the statue in the building near the fountain. Fireworks: Fuse Fire Moray, Earth Moray, and Water Moray by talking to the dude by the fountain in Bashea.
Golden Goose: they say you can catch it in 2-P mode, but the stupid bird kills itself before you can hit it once, so I just d-load it from LK1.
Doppleganger: Take on Katia's Responsibilities. (Woop her little butt)
Super Pumper: Catch in Proving Grounds, or get lucky and pick it at the end of the level in Proving grounds that it appears.
Lucky Lion: The ONCE-IN-A-LIFETIME card. U mite hate me 4 this post, but if you passed it up, you gotta re-start you're game to get it. Back in Sarvan, there are 2 caged chests. If you didn't get this one, then you took the all-impressive Hobgoblin. Sorry, but you can't retry. U gotta take this chest once you get a Birdman or something so you can fly to that island with the other caged chest.
There you go. I see these ones asked about a lot, so I decided to post my 2 cents.
In any level get 2 Rheebus's ( card no.082 ) and play one on the field while that one is on the field then put the other rheebus next to that one then both of the rheebus's will give each other health so they don't die.Now your other monsters and you can go on the grassy area of the rheebus's and you can heal and heal and heal as long as you want (it doesnt matter if your rheebus is attacked).