The Unholy cross-over of MLP and Hamtaro, in poster shape. Was also one the Japan Expo goodies! I was glad I remembered how to draw those hamsters without even trying, 13 years old me would have been proud. :,)
To add some words to this, I also thought their height to be a bit different for each of them, even if that disappeared to the sake of global composition.
Fluttershy is the tallest, the others are average, while Rainbow Dash is a bit smaller. She's the kind of hamster that's so small and run everywhere and that's like the plague to even catch her if she's out of her cage! Twilight is the smallest due to only eating books since her birth. Literally eating them.