I still have my Red version my uncle got me from USA in 1998, while the game was only out in France in 1999. It still works, although my brother erased my save with full legit completed Pokédex (except Mew which I used the glitch).
I also have a Yellow version which was my brother game, dunno if it still works.
I recently found at my parent's home some Japanese version of Yellow and Silver, I don't know why those games were there lol. Silver works but the battery is dead so no save, Yellow still has its save (pretty regular team: Pikachu, the 3 starters, Mewtwo and Aerodactyl), I'm not sure I can trade them in an US version.
Then I have the physical version of Pokémon TPP version, a romhack of Red made for the first anniversary run of Twitch Plays Pokémon. It adds a higher level curve (Brock is almost Lv20, rival at the E4 is Lv100), all Pokémon available to catch (you must complete the dex to finish the game), Gyms + E4 rematches (all Lv100) and a battle tent for money.
The Crystal hack is coming soon, I'll buy it too. It adds more stuff than the red hack, like gen 6 moves / type chart, new items, new story, new sidequests, all 251 catch etc.