I think it would be really cool to see the "most popular of all time" dress ups, but I don't think there should be a slide show on the main page (for problems mentioned).
Instead I would suggest that apon clicking the "Dress up Challage" button, on that first page you see there could be two more buttons atop the page for "Most popular of current challages" & "Most popular of all time".
Support! Think of all the MHA, BNHA, and other animes/TV shows/Movies there could be! I would die for this, it would bring some serious new life into my gameplay