Rebbi is an important Nimbi in The Flip Flop Show.
While in Sector Seven of The Overthere, Bleu encounters a Nimbi fighting the invading Skellobits. Upon Bleu's arrival, the Nimbi requests Bleu's help in defeating the Skellobits. Once his request is granted, the Nimbi - whose name happens to be Rebbi - gives Bleu the Red Orb, one of the three orbs required to build the bridge to Grambi's castle.
Later on, beyond the bridge, Bleu and his party are stopped by a massive squadron of Skellobits and Skellobombers. Rebbi shows up to help the heroes. After recovering his health and strength, Rebbi manages to gather a brigade of Nimbis, who then engage the Skellobombers in a fierce aerial battle, thereby allowing Bleu and Co. to head for Grambi's castle.
Official art of Rebbi.