If a hacker knew what they were doing and really wanted to, they probably could. But I imagine it would be a lot of work to do so, and even then they'd still have to fool subsequent checks outside of the game itself which will be much tougher. Why would anyone want to hack something that on the surface seems legitimate, including having memories to be read, as nearly anything else is going to stick out like a sore thumb. A Diancie in a non-Cherish Ball is so convincingly legitimate... /sarcasmSpeaking of which, is it possible for Kalos-born Pokemon to have memories even if it was hacked? Most sources seem to say that the Memory Girl is a pretty reliable first check but I can't find anything about whether or not it's possible to fool her.