I just turned on my yellow edition and the save is still intact. It is the save of my brother who deleted my original save back then 15 years ago, which saddened me deeply, since I was very young and it was my very first Pokemon game.
I wanted to replay it for a long time already and want to start today, but considering these Pokemon survived for at least 15 years it's kind of sad to delete them.
Is it normal that batteries last that long? I had that yellow since 2000 I think.