While chatting with some people group members on Facebook, we discussed the idea of having an "All Region Tour" in preparation for Pokémon X and Y's release in October. Some have even opted to make it hardcore by playing a Nuzlocke Challenge. For those who don't know, a Nuzlocke is a challenge where you can only capture the first Pokémon you encounter on a route. Additionally, if any Pokémon is KO'd, it must be released at the next opportunity. I am not playing a Nuzlocke personally. Anyway, here is the schedule:
May (Kanto) : FireRed or LeafGreen
June (Johto): HeartGold or SoulSilver
July (Hoenn): Ruby, Sapphire, or Emerald
August (Sinnoh): Diamond, Pearl, or Platinum
September (Unova): Black or White
You COULD play Red/Blue for Kanto and Gold/Silver/Crystal, however if your battery is dry you can't save those games. Also, you cannot send anything cool you come across up to X and Y. So long as you have the right systems something from FireRed could potentially be sent up to X and Y. Do keep in mind, you can't use Pokémon from one region in the next one, so no trading until you beat 'em all!
I just started FireRed with my Bulbasaur (named KickGrass). Good luck and have fun folks!