Nintendo already has one of the most popular AR experiences out there with Pokemon Go, so it would make sense if they took a second venture into AR. They have a wide selection of IPs to pick from, but the one I thought would work pretty well, and is more relevant because of its recent popularity boost on the Nintendo Switch, would be Splatoon 2. This is a franchise that grew despite the weak sales of the Wii U, gathering a fanbase that keeps growing to this date.
With Splatoon 2 the core goal is to cover the entire map in ink. Now imagine if that were in real life. With this AR experience, you would be able to completely paint the whole floor with ink without actually needing all that ink, and without Bendy haunting your nightmares for weeks. It would also offer a fun competitive multiplayer. This would have a local multiplayer experience that could be played anywhere, making it a massive hit. Because of the variety of weapons and play styles, it could change the way you play depending on the environment in which you start up the match.