Nintendo unveiled Pokken Tournament DX for Nintendo Switch today on Nintendo Direct. The game is an update of the Wii U version, an is scheduled for release on September 22.
The original 16 playable characters from the Wii U version will be included, plus five new playable Pokemon: Darkrai, Scizor, Empoleon, and Croagunk, plus Decidueye from Pokemon Sun and Moon. The game will offer 3v3 team battles, friendly and group match, plus ranked play online. It is likely some fo the online features will require a membership to Switch's online service, which will be free until some time in 2018.
A playable demo will be at E3 2017 next week.