YouTube Channel “Will It Work” has put out an interesting video.
In it, he attempted to use an Atari 2600 Controller on the Switch and found through the right adapters, it was not only possible, but with some games like NES Donkey Kong, it worked rather well.
There are a variety of retro games that utilize basic controls that would use this controller well, and that includes games in the Atari Flashbacks Classics Collection
You can see the video below
In addition, for access to an extensive variety of active retro gaming groups on Facebook, visit Retro Gamers Hub.