Oh, so that's why she wanted that to happen? I'm flattered, but...
Hmph. After all I've done for you I thought I'd at least deserve an A-. unless B++ is actually really good in those games and I'm just dumb
Yeah. Not one of the DS ones. Two of them have 3DS remakes that basically invalidate the originals with the amount of quality-of-life and balance improvements they add, while the third is better but still suffers in the QoL department compared to the newer games.
Instead I'd start with a 3DS one. All of the games except Nexus have demos on the eShop, so you can pick one of those up and see how it goes. If you want a specific recommendation I'd go for 5 or 2 Untold (the former is the second most recent, the latter has a story mode with preset characters if you don't want the hassle of making your own), but they're all good. The games don't have any important story connections to each other, so you can just start with any of them without feeling like you're missing out on anything.
If you must go for a DS one go for 3, but I dunno how well you'd manage to draw maps with an emulator (I've never tried, and I'm not sure if the DS games have the auto-mapping features the 3DS games have).