Well, since Birdo was originally in Doki Doki Panic, I assume this game will contain several Japanese characters that are obscure to Americans. But since Birdo started showing up in Mario games, it just strikes me as weird and a little dirty to see Birdo show up in a game that appears to have nothing to do with the Mario universe or any universe I know of. This is the only reason I can think of for a Captain Rainbow thread on the Fungi Forums.
But for the record, at times I like Birdo. I liked Birdo in Wario's Woods, although again I can't think of any reason why she (I know Birdo as the character with the female voice in Mario Tennis for 64) would show up there. Well, Birdo was called Catherine in Wario's Woods, which I like more because it sounds like a female name.
So there's three games I can think of that had both Toad and Birdo in them, Wario's Woods, Super Mario RPG, and Mario Tennis for 64.
...uh, back to Captain Rainbow... it almost looks good because of how far out there it appears, but their version of Birdo looks terrible. They should have just stolen a GameCube model of her instead, would have looked better and fit in more.