Nintendo has confirmed that the upcoming Pokémon RPG game for the Nintendo Switch is expected to release sometime in 2018 or later. The game was announced during Nintendo's E3 2018 livestream.
The Pokémon RPG game is currently being developed by Game Freak. The Japanese studio is known for its involvement in the development of several popular Pokémon titles for the Nintendo Gameboy handheld console, including Pokémon Red and Blue and Pokémon Gold and Silver.
The game's current working title is "Pokémon for Nintendo Switch", however that is likely to change once the game gets closer to its release in 2018.