I put, like, a Meowth in the day care once or something and it's really not worth it unless you have a Pokemon that literally can't defend itself like Magikarp. The day care will give you like a few levels after you've gone and trained for days so you have level 100 Pokemon and they're like "hooray! you're Pikachu leveled up by a factor of four since you've been gone!" Great. Thanks. Here's a million dollars.