The problem is that they don't work. Even if they do, it's not for very long and they almost never actually save your game.
Nothing about that is convincing though. Sure, it says Nintendo, but the label is all wrong, which means you needn't even bother popping the stupid thing open in the 1st place.
Still, I guess it's good to know that they're putting that there now. Just one more thing to look out for.
Luckily I couldn't care less about the Pokemans, so I'll never get stuck with one of these sorry-ass carts.