That is absolutely fake. The number one reason is you don't see the official Pokemon or Nintendo trademark logo. If it was official, you would see one of those. Two, it looks really poor quality. The pokemon used in the trailer, seem to be ripped from one of the 3D games. Another reason it is fake, there is no news on it. If it was real, I should be able to go on Google, and find something. Pokemon is the #1 in sales of children toys and games. I highly doubt they would sabotage or ruin that with some poorly budgeted film. At the very least, its a fan movie.
On the side note, a decent live action Pokemon movie has to be top notch. It has to be produced by Fox or Paramount, with a huge budget. Anything less will be some poor CGI movie. Transformers is one of the best examples I can think of for this. It had a huge budget, they used it well, and its popular. I bet we would see a live action Naruto before we would see a pokemon.