Title. Are there any features in older Pokémon games you want back? This one I would assume they would this trend, but character customization. There is just something I find so satisfying about picking outfits in the games, despite me hating fashion irl. It makes your character unique. And also hairstyles goes with this too. I like the hairstyles. A popular choice, but having your Pokémon follow you. It was one of the best features in HGSS. Also it’s in Lets Go, which means they are capable of doing it again. (Of course there would be over 800 Pokémon to do this for, though) One I’m dying for them to bring back, the PWT. It was such a good concept and honestly it worked so well. For the longest time, all I did in White 2 was play in the PWT and I’ve grown to love it. It would be even bigger and better, now that we’ve passed through 2 generations, and we can include the Kalos gym leaders and the trial captains. And also Diantha and Hau to the Champions tournament, and maybe even an E4 tournament. The last one I want to share is the friend safari. I think it was one of the best things to come out of X and Y. Since the switch also has a friend code system, the friend safari could work.
Bring back Gyms and Badges, please? I applaud them for trying something new with the Island Trials, but a lot of them were too hard, repetitive, and confusing. Also bring back alternate career paths besides trainer--with the jump to a big console, you could easily bring back Contests and possibly something brand new. Join Avenue (or something like it) would be cool to see again as well--you could expand it so that past Gym Leaders/trial captains from all generations could visit it Build on the Pokémon Musicals to actually be something fun, inside of dress your Pokémon up and then sit and watch then dance for five minutes.
All of them. I'm actually fed up with GF cutting corners with Pokémon titles; there is absolutely no reason why things have to be "unique" to certain generations. Put everything in these games and make them better than everything that has come before. Give us following Pokémon, day and night, seasons, character customisation; all of it. The Switch is substantially more powerful hardware so the only reason not to do this is pure laziness.