Better interaction with your Pokémon
Pokémon are monsters you capture and do battle with other trainers. Is that all there is to your relationship though? Are they just creatures you cruelly force to do battle for your personal gain and amusement and then trade away when they aren’t of any more use? I would surely hope not.
In that spirit, for Sword and Shield for the Nintendo Switch should provide a wealth of activities for you to do with your monster friends that has nothing to do with battles. Give them affection with pets and treats like you can in the Let’s Go games. Maybe have them participate in races with other Pokémon. Give them a spa treatment at a Pokémon Center. Maybe they can play soccer (actually, get someone on that and make it a separate game).
These activities should be optional as I hate nothing more than being forced to do side activities. However, if you really want to feel like you and your Pokémon are friends that share a deep bond, you’ll voluntarily engage in these because it’s something you would do with a pet who is like your best friend. It’s just something that enhances the experience and makes the Pokémon feel more real in the game than if they are just things you collect, battle and trade.