Bad news
He'll/She'll probably have to restart, the risk of AR is that if you put in the wrong code, or put a code in the wrong way, your going to be one depressed person.
Try trading with your friend or have the person go to the PC.
I never cheated, thats how I have 328 poke'mon on FireRed, I transferred 237 poke'mon from Sapphire to FireRed, all caught without cheating. I even have Jirachi, Deoxys and Lugia. And I Borrowed some people's GameBoys and took their Rayquazas. =D At first, when I completed the game, I wondered what to do next, and from the moment I saw Rayquaza in the book, while I was at my friends house and yelled at him "HOW DO I GET THAT POKE'MON?" and was adicted to Rayquaza ever since. I trained all four of them to level 100. And I caught or traded, without Gameshark or AR, when I used it on my other versions, it just wasn't fun anymore, trying to catch it, they just appeared, more common than Pidgey and so on.
The moral is, use AR or GS, you could blow all of it away.