I actually have a couple of questions on this topic, for those that have a bit more experience here:
1) Did the bell saver badge change? I took a 5 year hiatus from this game and only came back to it last summer, aka after the big update. I could SWEAR the bell saver badge used to be 100,000,000 bells, but now it's a billion? Can anyone confirm or debunk this? (And if it really was changed, man that's a SUPER crappy thing to do, Nintendo.)
2) For the Streetpass badge, are you able to Streetpass the same person repeatedly, or do they all have to be unique? I know this requires the DSes talking to each other. Does this require that they're only in standby mode, or will they do it while you're in-game, too?
3) I'm nowhere with my turnip trading badge because I've just generally never bothered with turnips, but I had recently thought I should start working on that and hopefully get the badges. I bought turnips and intended to sell them later, and because my life doesn't allow me to play completely regularly I made sure I kept track of the last times I played because I have to TT a lot and I didn't want to accidentally go backwards. Despite this, my turnips still spoiled, and I was really confused. I change the clock on my DS itself rather than the in-game one, so I don't know how the game knew I'd gone forward in real life and artificially moved it back. I do regularly go to Club Tortimer though because I'm still missing 3 items, so I was wondering if that might've spoiled my turnips? Does the game check your date/time against the world clock when you go online?
Sorry this ended up being so long! These have just been on my mind for a while because these badges are giving me so much trouble!