Pokemon is the second bestselling franchise of all time, having sold over 200 million copies worldwide.  That places it narrowly behind Mario (222 million copies) and well ahead of third place Tetris and The Sims (125 million copies, each).  The franchise's incredibly addictive formula of combining the pet monster and RPG genres has proven pure gold and shows no signs of slowing down.

Now Nintendo is preparing to yet again reinvent the series with the upcoming Spring 2011 release of Pokemon Black and White for the Nintendo DS (September 2010 in Japan).

The new title is perhaps most noteworthy in that it will bring 3D modeled and textured backgrounds to the series' handheld titles for the first time.  The graphics seem reminiscent of certain PlayStation titles in that they feature a 2D sprite drawn on top of a mostly 3D-rendered background.  Monster battles will also feature some mild 3D effects by the looks of it.

As if the Pokemon franchise needed more tools to addict our youth, it is now offering increased networking to allow gamers worldwide to compete against each other.  From a trailer video its clear that the game can connect via Wi-Fi.  

The game's cover beasts have been announced to be White Yang Pokémon Reshiram (????Reshiramu) for Pokémon Black and the Black Yin Pokémon Zekrom (???? Zekuromu) forPokémon White.   The game features a host of new monsters and the return of many fan favorites, as usual.

For Pokemon fans, about the only disappointment is that the franchise continues to lag behind Nintendo's hardware releases.  While the Nintendo 3DS will launch this holiday season, Pokemon won't get any 3D-display loving until at least mid next year (no dedicate 3DS support has been announced for Black/White).  So you will soon be able to get your latest Pokemon fix, just don't expect it to blow you away with 3D-display technology.

A full trailer of the upcoming title [in Japanese] can be found here.