For fans of the original Pokemon Red and Blue (or Red and Green in Japan), you might be interested in the recent four part anime Pokemon Origins which takes a look at Red's journey through the Kanto region to become the greatest Pokemon master and to complete the Pokedex for Professor Oak...basically the plot of the games.
Pokemon Origins definitely differs from the Pokemon anime we have now in a couple ways. First, the four episodes chronicle Red's trip through the Kanto region in full, all the way up to the Pokemon League and...well if you've played the games this isn't really a spoiler, but also through the Cerulean Cave you can go through after the Pokemon League. Also, Origins sticks really close to the games whereas the main anime series kind of goes off the main path now and then, such as with Team Rocket. Overall, it's pretty well done...but I do have one issue with the end. I won't spoil it, but it's something I wish they hadn't have done, but I can see why they did it.
To check out the series, head on over to the official Pokemon website.