Wilren said: Wouldn't their entire decks be nothing but Spell Cards, though?
If we can have Trap Monsters, who's to say they can't have Spell Monsters? :V
Still, I imagine to cause this sort of scenario Yukari would gap in a shipment of packs, and by the end of the day everyone'd have some kind of deck going (e.g., Aya with Blackwings, Patchy with Genex, Alice running Karakuri, etc.) as a result . . . and Rinnosuke would be a happy man, for he'd finally have bloody customers.