GameFAQ member Vergeben has revealed new information regarding Super Smash Bros. on the Nintendo Switch. The users source (who was also the one who revealed that Metroid Prime 4 was being developed by Bandai Namco) revealed that it will be a direct sequel to the WiiU/3DS game and reuse many of the assets.
As far as characters, this source says that Ice Climbers, Simon Belmont, and Ridley will be coming to the game. All other characters from the Wii U/3DS game will also be returning. This same source also said that Ridley will be revealed at E3 2018.
We are classifying this as a rumor due to the use on anonymous sources.