My predictions:
1) Paper Mario characters (Mario is one and other classic Paper characters would be other skins).
2) Goku. Fighterz and Xenoverse 2 were on Switch, and those are actual well received quality games, not movie tag along titles.
3) A snipperclips. Would be hilarious like Piranha Plant and Wario lol.
4) Doomguy. They have done a lot of effort to show support this gen.
5) The Witcher.
6) Robot Reggie. I'm not joking. Make a legit character with laser eye powers and body slams. Voiced by Reggie himself. People in the USA would flip like nothing since Banjo announced as a character.