I still have all of my old DS games, with both of our old DS systems, in an old Pikachu-themed backpack from kindergarten in my wardrobe. They all still work, with the same original save files on them. I rarely have time to revisit them, but when I do I get very happily nostalgic. Our oldest one (and in fact first DS game) is Pearl, and I also have Black, Ranger: Guardian Signs, Mystery Dungeon Explorers of Sky, and an old second-hand copy of Emerald.
That last one can glitch sometimes and doesn't have a box (it resides in Pearl's box, DS game boxes have place for both a game card and a game pack), but all other games have nearly pristine-condition boxes and manuals. We were always careful with our toys, especially the expensive consoles, and games were in our eyes delicate things you handled with the tips of your fingers and utmost care. Seriously, I had a Ranger game where you have to spin the Capture Styler with the stylus very quickly, and my touch screen hasn't got a single scratch. That's how mindful we were of our Nintendo.
In the box for Wii equipment I still have both of the Poképark games. These also still work and have original save files.
Bonus: my true introduction to Pokémon games was on the emulator, the same one I still have on my computer, along with the games and save files, some of which are way back from first grade.