I haven’t spend that much time on this research I must say because there are just so much other things to find out aswell but whenever I think I see any possible weld line I have been screenshotting it. I do plan on making a good summary and explanation in a separate thread but I haven’t got the time to do it just yet. Therefore I make a quick summary of what I got so far but I actually have screenshots of lines that I think are different versions than these ones. So these seven examples are the different ones I have seen so far, not all of them create the nice looking double swirls but they are overlapping weld lines nonetheless. indeed the slowking (not nidoking 
) picture @smokemon posted is the same as example 3
To be continued 
Edit: the way I try to recognize these weld lines in my search of needed data to confirm these things is I look for these interrupted orbs/ globes. Example of Moltres is one I spotted yesterday and still need to be compared to my made examples so I’m not sure yet Hat is going on. It just shows how I spot these things. 
