The original Kirby Fighters game was a mini-game within the 2014 Kirby: Triple Deluxe Nintendo 3DS game.
Nintendo released an enhanced stand-alone version titled Kirby Fighters Deluxe for the Nintendo 3DS via its eShop in the same year.
Nintendo’s website is listing a “Kirby Fighters 2” game for its Switch system.
(The listing can be seen by heading to the Nintendo website’s Game Finder and clicking “Nintendo Switch systems” under the “Which system do they play on?” drop-down menu.