He's talking about HG/SS. The 4th gen introduced the "Anti-Little Brother" feature, which makes it so you can't save in a new game without first erasing the old file. To do that, you have to press Select+Up+B (I think) at the title/menu screen, it'll ask if you want to erase your old file and will once you choose yes.

I've only done this twice, so I can't really remember the exact details of it. Plus I have a psychological fear of data loss (not kidding, there are some nightmares where my computer deletes stuff and my DS games lose their saves) so I really don't even want to see the screens most of the time.

If you have those kind of nightmares, then I suggest you treat your computer and DS better. Maybe then the nightmares will go awayz.

Jeez, I wish they had thought of that earlier. Thanks to my friend's little brother, my Emerald team that had 7 of 9 starters in the 60s+ was erased.

then I suggest you treat your computer and DS better.

Oh, I do. After going through that wonderful reproducing virus which made my last computer have amnesia, I do a lot more to protect my new one. I guess the game data loss just stems from my old Crystal and when my Platinum almost died due to too many codes (couldn't read the save for a good hour).