The cold hard truth is that Poliwhirl represents the creative heart of what Pokemon once stood for, but Pikachu was chosen instead because it could better convey emotion and it could "communicate" better. It was also simpler in concept whereas Poliwhirl would drive up expectations on individual 'mon designs if it was the mascot. Oh and Poliwhirl would have been put through the ringer and changed multiple times like Pikachu did even if they chose him, so I don't give a damn. He was once mighty, that's good enough for me.
