The Earthbound Immortal series can be found in the following booster packs:
In Phantom Darkness pack unlocked chapter 4 Yubel is a common card Yubel-terror incarnate is more rare than the standard Yubel and Yubel-the ultimate nightmare is as rare as E-hero rainbow neos and Rainbow Dragon which are in the same pack as the Yubel cards you can also get the earthbound immortals,signer dragons,god cards,Nordic god cards,sacred beasts and the wicked gods Source:gamefaqs.com
"Earthbound Immortal Chacu Challhua" comes in the booster pack Ancient Prophecy.
A regular/ standard booster pack of Yu-Gi-Oh! cards contains nine cards - one of them guaranteed to be Rare or of greater rarity. The Duelist Packbooster packs only have five cards inside. The Dark Beginning, Dark Revelation, and Dark Legends booster packs have 12 cards inside.
The Phantom Darkness pack has Dark Armed Dragon, it's very rare and valuable though. From what I hear it's hard to get him even if you get boxes of cards
get the card pack force of the breaker
First you need to beat the game. Then you can either talk to Crow who's south of the satellite then he will tell you about a shadow where you dueled kalin. Beat that shadow in a turbo duel then talk to crow again to unlock a pack containing a few earthbound immortals. Also after you beat that shadow you can then go to where you dueled Roman. There's another shadow there to beat for another earthbound immortal pack, but you will need to talk to crow after you beat them. Also you can talk to the MC in the fortune cup and he will tell you about another shadow in the duel stadium. Beat that then talk to the MC again to unlock the pack for some earthbound immortals.
It comes in packs of Stardust Overdrive.
In Phantom Darkness pack unlocked chapter 4 Yubel is a common card Yubel-terror incarnate is more rare than the standard Yubel and Yubel-the ultimate nightmare is as rare as E-hero rainbow neos and Rainbow Dragon which are in the same pack as the Yubel cards you can also get the earthbound immortals,signer dragons,god cards,Nordic god cards,sacred beasts and the wicked gods Source:gamefaqs.com
Walmart or a yugioh store.
You have to but the Super Polymerization Overdrive Pack. It features both Yugi's and Jaden's cards. TO unlock the pack you have to get 30% complete card packs from 49-57.
you could go to target. a 16 pack cost $0.99. or there is a shop that sells cards at the mall
You get a movie pack which contains 5 cards. There are 9 cards total in the pack list. There is a good chance you will get a Malefic Red-Eyes.
"Earthbound Immortal Chacu Challhua" comes in the booster pack Ancient Prophecy.
raging battles pack majestic star dragon or wiroqocha rasca tin ancient prophecy only for vayu
The list is fairly long, so here's a link to the list from the Yugioh Wikia: yugioh.wikia.com/wiki/Ancient_Prophecy
The legendary Six Samurai are a new archtype in the yugioh card game world that are coming out in the storm of ragnarok booster pack coming out feburary,9,2011 if you play yugioh with six samurais you should get these cards
you can get rare cards in a normal yugioh pack by buying booster pack and starter decks. e.g. i got ocean dragon lord neo deadlus in a furry from the deep deck. And ocean dragon lord neo deadlus is a ultra rare card.