You have probably already run into the Wal-Mart posters already. They were some of the coolest items we have had pop up since season two ended. A few days ago, the designer of the powers, Nayuki, dropped a bit of information on his initial ideas that were eventually canned.
Have some copy paste, also found in the image above:
Villain' Poster development:
Location - Everfree Forest
Story - Trixie has set up her stage show and is challenging the other 'villains' to a game of 'Anything you can do, The Great and Powerful Trixie can do better'. Discord is on the stage pulling a rabbit out of Trixie's hat (the rabbit in this case is Diamond Tiara with the bunny ears from Family Appreciation Day).
It was scrapped due to composition issues.
Location - Saloon in Dodge Junction
Story - The 'villains' are all gathered in a saloon. There is a stage in the corner with the Trixie/Discord gag from the first poster attempt. Flim and Flam are serving their Apple Cider at the bar. NMM, Chrysalis, Gilda and Iron Will are playing poker at one of the tables (Gilda is cheating to win). The Diamond Dogs are at another table counting gems. Garble is playing a piano (similar to when Spike did it in Over a Barrel).
It was scrapped because of the possible alcohol/gambling reference.
Version 3 (the one that ended up getting made at the end):
Location - Discorded Ponyville
Story - The 'villains' are gathered for a friendly group photo.
Note: It isn't really so much a 'villain' poster, it's more of a 'antagonist + monsters' poster, which allows for more characters in the poster and avoids the arguments of who really counts as an actual villain.
Sounds like you guys need to get to work on making these a reality! And be sure to give Nayuki your thanks for getting these things created. The group shot posters are a blast!
And thanks to Jordanolling for the heads up!