After you beat Yu-gi in the Battle City finals, he will obligingly hand it over.
Chat with our AI personalities
you have to beat the game you have to beat the game
Sacrifice 3 cards to summon
It can be attained via Action Replay as of now. They are beginning to release Egyptian God Cards for download on Wi-Fi. Slifer the Sky Dragon has been available for download.
Unfortunately, no previous YGO! DS games can link with World Championship 2008, so you cannot get the God Cards from Nightmare Troubadour. I know for a fact that "Slifer the Sky Dragon" was offered as a downloadable card for one day, so perhaps that is the only way of getting the God Cards. yes ghosts exists.
Because there are no official rules for the Egyptian God cards, the only reliable way to destroy "Slifer the Sky Dragon" would be to destroy it in battle with a monster with equal or greater attack. This can be accomplished by using "Honest" while attacking/ being attacked by "Slifer", discarding cards from your opponent's hand to lower its attack, and more.