Rexbert

Rexbert is a great tit who sells ground branches, ground using sick skater moves. He calls what the wiki calls "canon" the "Big Three".

Base
Rexbert looks like a standard great tit, he's round with the design of an Omnitrix upon him.

Transformation 1
Rexbert looks the same, except that his "segments" of color are now separate, revealing a glowing "core", and his legs are gone.

Personality
Rexbert is really cool, in fact, he's the coolest bird in the Sandsverse aside from Coolberd. He likes numbers, a trait that shows through in his vernacular, with more "to"s and "too"s turning into "two"s than any other transformation of that triangle.

Relationships & History
His first big rivalry was with Chunk, which stated with Chunk suggesting that Rexbert kill all two of his followers.

Jeremy had allied with Rexbert even though he "so thoroughly grinde[s] [his] branches", before Rexbert accidentally insulted dogs in an epic rap battle with Alfonse and Jeremy snubbed him.

Deceit enjoys telling Rexbert (among other vendors) that he is not real, and as such, Rexbert distrusts him.

His second rivalry is with Isabell, which started when Rexbert rightfully called her not round and climaxed in an elemental battle between the two. They are now bordering between vitriolic best buds and friendly rivals.

Misc History
Rexbert won the Spirit World Elections because of Jackle spending all his money on sludge and Isabell being too irresponsible to govern. This makes him the Spirit King.