I looked at using the new sets mermaid for you and or the fairy one, but I couldn;t see a rainbow in there.
So I grabbed and old one but favorite stampset. Monstermash from Lawn Fawn ofcourse.
I believe monsters can be any color!
I stamped the images with My Favorite things hybrid black ink onto Schut 300grams watercolorpaper.
I used Distress inks for my watercoloring (from left to right: wilted Violet, candied apple, carved pumpkin, mustard seed, mowed lawn and mermaid lagoon)
When finished I mixed all the left over ink to make dirt, so I could ground the monsters.
Mounted the panel with foamtape and stamped the sentiment with Versafine black onyx ink on the cardbase.
I added lashes to the green monster to make her girlie (red lipstick) and on the green and orange I added Wink of Stella and on others googly eyes.
I thought about adding some sequins, but I didn't ;-) I like the focus to remain on the panel.
For more information on the Lawnscaping challenge, see this