Beat him with Cerberus first try. Not sure there's actually a threat other than Rainbow Dragon or not, he clogged his S/T zones too quickly for me to see anything other than Bond and Release.
Beat him with Aromage, stalling until he decked himself out, it seems Rainbow Dragon and Crystal Release equipped to a CB are the only threats he have, and even then Rainbow Dragon auto dead to battle position changing cards.
Also, the way he swarm monsters even after Rainbow Dragon is out, means WOD troll his deck hard. Especially if you wait and use WOD when Rainbow Dragon attacks your monster.