A Nintendo Direct just happened todayOkami HDDark Souls: Remastered
Little Nightmares Complete EditionSuper Smash Bros. is coming to the Switch this year. The video teaser (shown below) shows that the squidkids from Splatoon will join the fight.

Luigi's MansionCaptain Toad: Treasure Tracker is coming to the Switch on July 13. It is based on the Wii U release but will have some additional levels based on Super Mario OdysseySouth Park: The Fractured but WholeSplatoon 2
UndertaleCrash Bandicoot N-Sane TrilogyHyrule WarriorsMario & Luigi: Bowser's Inside Story and Bowser Jr.'s StoryMario Tennis Aces. The game will be out on June 22, 2018 for the Switch.