Let's admit it, this is RD's brother, one of the many "Rainbow _ash" siblings of hers. They're all the same except their cutie mark (which always has a cloud), fur color, and first letter of second name. We got Rainbow Smash... he's green. Rainbow Cash, she's gold. Rainbow Rash, who's red. Rainbow Trash, who's orange. Rainbow Splash, who's white. Rainbow Flash... well, the list goes on.