Get big and strong! She'll play with you even if you're small, though. It's not like she's really big...

"For some it depends on levels, or how strong they are. Others need particular stones. Cubones... just evolve after enough experience, if I remember correctly."

It's been a while since he's read anything about them, but that sounds right. "Eevees can evolve into one of eight different possibilities, which is the most out of any Pokemon seen so far. The Umbreon evolution happens when they have a close bond with their trainer and they gain enough experience at night."