So um, if you don't understand what I meant, take a look at this image. Focus on Aron and Smeargle.
You see, Aron seems to have a single, thicker white line surrounding it unlike Smeargle who has multiple but thin white lines. What are the difference between these spawns?
Also I noticed that sometimes spawns with thick white lines seems to be encounterable even if they're off range from me. But that could just be my laggy ahh GO.