[mdom]

Commons with rainbow hair we have... well, you can look for 'chromatic' in the shops xD there are a few. Entirely rainbow only the Bouncing Beauty and the Devoted ones. Uhh and scrappy bangs. Flat bangs and dragon ridge (a kind of mohawk) also come in rainbow.

Backgrounds I know you have the rainbow peony xD I'm using mine with the starry sky behind. My rainbows are irlandeza blessing and Rainbow Magic. There are also the fireworks of the new year, they have a rainbow pose.