It doesn't evolve at any specific level. It evolves via Happiness. Catch them in a luxury ball and/or let them hold the Soothe Bell to make them friendlier. They become happier if you groom it, give it vitamins, if it gains a level and if you walk about 250 steps with it being first in your pokemon party and it walks with you, giving it berries, etc.
Their happiness goes down if you let it faint, if you deposit it in your PC, and if you give it Energy Powder, Heal Powder, Energy Root, or Revival Herb. Also, if you trade it, it resets back to the happiness level when you caught it. Hope that helps :)
Their happiness goes down if you let it faint, if you deposit it in your PC, and if you give it Energy Powder, Heal Powder, Energy Root, or Revival Herb. Also, if you trade it, it resets back to the happiness level when you caught it. Hope that helps :)