>>37361110We don't know for sure just yet, but there's a feature to this one that makes it unique from previous iterations of the Nano: it has two games instead of one. My guess is which games are played and how often they're played will have some effect on how Eevee evolves. Also, the Pokemon blog said Eevee evolves after a few days, when the previous Nano versions have all evolved after 24 hours.