I forget exactly how I got back into Rainbow Brite specifically but I know it involved a conversation about the Transformers movie in the OYT chat room evolving to include GI Joe and other early 80's cartoon shows. Being the guy that I am, I immersed myself in Rainbow Brite for a day and started bringing up the show and character whenever possible in the chat room. Since a lot of the chat room sessions are devoted to NB's new game system and CJM's pimping of the Mutants & Masterminds system, I eventually decided to make a Rainbow Brite character (using M&M only because NB's system is a work in progress).
The character is extremely basic right now. My Rainbow Brite borrows heavily from the show but has a few differences. He is a guy named Brian (after the boy in the cartoon) instead of a toddler-esque girl named Wisp (although Wisp, which is Rainbow Brite's original name, makes a cameo as his girlfriend, which is important as we will now see). Despite all the rainbow imagery he is NOT gay. He has a girlfriend but for the most part I want to play him as asexual (i.e. I do not want his sexual orientation to come up at all; the better to avoid the other players making gay jokes).
He utilizes the M&M powers of Color Control (his prime forte), Emotion Control (Rainbow Brite made things colorful to make people happy and feel good), and a bit of Telekinesis or Flight or Entanglement (Rainbow Brite's rainbows allow Starlight to fly and are often used to wrap up bad guys or grab things).
Starlite makes an appearance as himself, except his name will be Starlight. He is a talking horse with a very high opinion of himself (regularly referring to himself as The Most Magnificent Horse in the Universe) and the ability to run atop rainbows, allowing for a limited form of flight when ridden by Rainbow Brite.
Twink will not be making a regular appearance for two reasons. One, I plan for Rainbow Brite to get his own star sprinkles (or have them delivered by an unnamed sprite every once in a while; just an issue of continuity rather than a plot point to get kidnapped) and two, the name Twink is just asking for gay jokes.
My Rainbow Brite always carries a bag of Skittles. They are his favorite snack and the manner in which he mundanely conceals his magical star sprinkles from others. He has adopted the Skittles catchphrase as his own (possible while using a rainbow to telekinetically punch a bad guy): Taste the Rainbow!
My Rainbow Brite is seen as semi-delusional because he believes in the Color Kids and their transdimensional, otherworldly home of Rainbowland where color crystals are mined by sprites and refined into star sprinkles which are then distributed to the Rainbow Brite on each inhabited world in the universe (he is Earth's Rainbow Brite and this is the excuse he uses for having Rainbow Brite as a name - all of them are called that) to utilize in spreading color and happiness. There is even mention of a previous Rainbow Brite in the Bible (Joseph and his Coat of Many Colors). Whether all this is true or not is entirely up to the DM. If it is true, then Rainbow Brite has a magic key that, when placed into any lock, opens a doorway to Rainbowland.
Appearance wise, Rainbow Brite appears as Brian did in the cartoon. He looks and dresses like a normal guy but is completely swathed by a rainbow color scheme. The top right of his head is red and the bottom left of his foot is violet with each color in its place between them. Using his color control power he can appear like a normal human with insignificant effort (he is a normal human, not an alien).
He also uses the color belt and rainbow sphere. He says they were given to him by the color kids in order to make him into Rainbow Brite. The belt can be used to generate semi-solid rainbows (for Starlight to run on or to wrap up bad guys) while the sphere allows him to colorize and brighten the world. Either one requires a star sprinkle to work.