Piracy, me hearties, has become a prominent issue for the DS, and one that is probably here to stay -- indeed, illegally downloading games to play on a flashcart has become almost socially acceptable in some places. And here's the biggest problem: it's not very hard at all to indulge in the practice. (Perfectly legal) flashcarts are available widely and cheaply, and ROM sites are a single Google search away.
In other words, finding solutions is difficult, to say the least. Chrono Trigger demonstrated that built-in piracy checks don't exactly last long, though Level 5 might have hit upon a semi-solution with Ni no Kuni: The Another World: deny the pirates the awesome spellbook that is required to play. Put yourselves in the shoes of a videogame publisher on the verge of releasing a major title: what anti-piracy measures would you take to try and protect your game?