pancher@gmail.com

To add to the last comment: I didn't see some of the characters in the screenshots and got a few different ones, but as soon as batman walked in I got the achievement. He was my 5th different cosplayer (had 2 robins show up). So it's either batman or 5 different characters.

OK, so I'll add my experience here:
1 - I was getting cosplays before 40Y. You just need to reach "famous" status and cosplay guys will show up.
2 - I think it has to be batman. I didn't get achievement until he walked into shop. I thought achievement required all of them at some point but I've never seen dude with glasses and tie in my shop (but I might've missed him). Anyway, all or only batman, that's my guess.

Any level. any store.
once you reach 40 year above the cosplay will walk in to your store, you need to click on the cosplay.

What is the difficulty level ?

Did you open all types of store ?