Rainbow Batman
In 2006, the Minimate Multiverse forum had a contest to recreate comic book covers with Minimates. I had a lot of fun making my entry, and was looking forward to competing in the contest again. I already knew what cover I would do, too - the Detective Comics cover for the Rainbow Batman story. So a few months after the contest was over, I got my hands on a bunch of the C3 Mini-Flyer Batman Minimates (the best Batman Minimate at the time) and made these customs. That way when the second contest was announced, I would have my these ready to go and I could concentrate on the artwork. And I put the finished customs on my shelf and waited for the contest announcement. And waited. And waited. And it never came, so I forgot all about my plans.
So then in 2010 when a new Minimate poster contest was announced, I kinda thought about entering it. Then I remembered my Rainbow Batmen customs and knew I had to enter, if only to justify the time I spent making these. You can check out the complete poster over here.
So why is Batman having to wear a multitude of colored costumes? It's because Robin, in his civilian identity of Dick Grayson, injured his arm trying to stop some thieves. So Batman wore a different colored costume every night to attract everyone's attention until the thieves were captured. That way the thieves wouldn't notice that Robin was injured and figured out he's Dick Grayson. Or, y'know, he could have just left Robin at home...