Since E3, developers have gotten creative with their teasers. Namco started the trend of dedicated teaser sites—which is currently in its final days (more on that here)— few days back, and now Game Freak, the minds behind the handheld Pokemon installments, has followed suit.
The site is simply a fluorescently obscured outline (which may or not may not be a Pokemon) and a wall of kanji reading “That classic game played around the world is reborn in a surprise collaboration.” So, the possibilities are many. We can, at least, assume that Pokemon will be involved to some degree, but the word collaboration is particularly interesting. Dozens of tie-ins exist for the handheld market, and Pokemon’s structure is malleable enough to be stuck with practically anything.
Shin Megami Tensei X Pokemon, maybe? Probably not. Perhaps Digimon will be involved? Or is the surprise collaboration something internal to Pokemon, such as a culmination of eras? We know little at this point, but will keep you up to speed as more information crops up.