I just would like to know if you can. And if so, how do you?
An easy way to do it would be catching a Pokemon that knows spore(list), going to the restaurant in Lumiose city and double battle with someone.
In the battle you can use Sketch on the Pokemon that has Spore.
If I recall correctly the restaurant is a bit pricey, but it's worth it in the end if you ask me.
You can't catch a wild Smeargle with Spore. However, you can catch Smeargle which can learn any move using Sketch. So, yes, you can get Smeargle with Spore.