Multiple sources tell Eurogamer the game is already well into development, will launch in 2017, and currently holds the codename of Pokémon Stars.
Earlier generations of Pokémon games have featured a third title launched later with expanded features - Pokémon Yellow followed Game Boy originals Red and Blue to start this trend, which continued through until Pokémon Platinum followed Diamond and Pearl on DS.
With Pokémon Stars, this idea will be revived - but for the first time we'll see the mainline Pokémon series spanning separate Nintendo consoles within the same generation of games.
Indeed, Switch will be the first Nintendo "home" console to receive a main Pokémon adventure. It only took 20 years.
Nintendo's new 3DS duo Sun and Moon, available today in North America and Japan or next week in Europe, have shared much of their development with their Switch bigger brother.
As you might expect, Pokémon Stars is being developed by the Sun and Moon team at Game Freak, the studio behind all main Pokémon games since the series' Game Boy beginnings.