In the cafe warehouse, what Pokemon do I give the used napkin to?
Okay so the guy on Sunday who gav eyou the Grubby Hanky... You give it to the guy with a Patrat. I think his there on Thursdays. Not always there :L
You give it to the person who owns a Patrat on Thursdays.
Hope I helped. :) Source
You give it to a customer who owns a Patrat. The Trainer will only be there on Thursdays though, so you'll have to wait a week. :3
Source: Experience