Ok this is what i personally feel and i think this is the only practical possibility. They are not fake. We can't prove them to be fake. Simple. We have seen it with our own eyes. People are not so foolish to believe whatever we saw till now is fake. Most probably, 98% they are real. Again such a huge game HAS BEEN LEAKED. However, if you want to believe these are fake, then the only possibility i can see is that this was a massive troll from Nintendo. A MASSIVE PLOT. I don't think those leakers were part of the troll team. But they were trolled as well. Because these are revolutionary games , something completely new for the Pokemon franchise and the past history that GF has faced with games leaking, maybe just maybe they plotted to defeat the leakers. AGAIN I REPEAT THIS HAS A VERY LESS CHANCE OF HAPPENING. Two reasons why i feel this has a 2% probability of coming true.
1) All the pokemon that have been officially released are world class compared to those leaks. Come on lets stop kidding ourselves, the new designs are not actually World class. Seriously Avalugg?? Diggersby?? even the starters? Ask yourselves are you completely satisfied with the starters?I am not saying they are bad, but they are not awesome either. If you are still gonna come out an d say that you are happy, then good for you but i have seen on most of the social networking sites like Twitter and Facebook and many communities, they are NOT SATISFIED with the starters. The response is very mediocre. Also Hawlucha, there is something fishy about that pokemon in the sense that it was see-sawing between fake and real for the first couple of days.
2) The fact that there are only 70 Pokemon and Nintendo has not put any effort at all to stop the leaks. And major sites like serebii have not posted anything regarding it.
Again i repeat this has a really less probability of happening 2% or even less., but you cannot completely write them off. This is a HUGE Game mind you. A revolution in the franchise, no reason why they can't come up with a different tactic to avoid leaks.
If i worked for Nintendo i would totally do something like this to prevent the game's leak.