Bayonetta 2 is coming out on the Wii U as a standalone title. It was previously released in a package with the original Bayonetta, which was previously only available on the PS3 and Xbox 360.
The new release of the game will be available at $30 on February 19. It's currently available for $50 on the eShop, so you should probably wait unless playing the game immediately is absolutely dire.
The physical version of the game is difficult to find and is currently only available from specialist sellers at more expensive prices. Nintendo has not announced any plans to bring the game back to retail at this time.
The game's titular character will be playable in Super Smash Bros. as its final DLC character.
