A Twitter user posted photos of what appear to be an official TPCi (The Pokémon Company International) presentation in which Pokémon Dash Mobile was revealed. Account in question has now been made private, but seems to be someone with ties to their PR firm.
From the screenshots included in the slide it looks like the game could be an endless runner akin to Temple Run or similar games that have gained popularity on mobile devices.
More slides seem to be about other mobile games, including Pokémon Co-Masters coming to the West as Pokémon Board Master
Although it did seem that the account could be legit (cross-checked with LinkedIn) this is not confirmed.