Digital UM Crashing

Digital copy on 3DS of UM, no mods, no jailbreaks, but i haven't opened it in a really long time. I went into the save file it had (which wasn't all that far in), ported like 7 mons into Pokébank, then reopened UM to wipe save, intending to try a nooby nuzlocke. I've obtained Starter, and thankfully the game saved RIGHT there, but everytime I enter the Tall grass, a ratata spawns, and game crashes. Battle Buttons never make it to the screen, and device hard shutoff is the only way out.