Playing Pikmin 1 on switch right now, the game holds up very well for its age,
As for remake games, an easy one is just porting Wind Waker onto Switch. I think Double Dash is my number one game I'd like to see come to Switch, but would also like the Fire Emblem games from the 3DS on Switch. I think Dire Emblem Fates would sell very well, and Awaking and Echoes: Shadows of Valentia could also do well