https://www.polygon.com/2018/12/3/18123849/super-smash-bros-ultimate-pikachu-eevee-spirits-pokemon

The Pokémon Company revealed that Pikachu and Eevee are coming to Super Smash Bros. Ultimate — that is, spirits based on the characters and their Let’s Go! designs. Collectible power-ups inspired by the mascots will begin showing up in the game’s Spirit Board rotation starting next week.

The Japanese Pokémon Twitter account confirmed that the Pikachu and Eevee spirits will arrive Dec. 14, but they won’t be accessible to all players that day. Instead, only those with save data from Pokémon: Let’s Go, Pikachu! and Let’s Go, Eevee! will receive the spirit analogous to their saves. They’ll get one automatically, as opposed to everyone else, who will have to cross their fingers for Pikachu and Eevee while playing the Spirit Board lottery.