Bleach should be counted too? As we know the series started with Ichigo and Rukia hunting hollows but then when the Soul Society arc kicked off the series became more of a normal shounen?

I don't think Dragonball counts. It was always an action series and thus you can't really call it a genre shift. It shifted from being more fantasy- and comedy-oriented to being more sci-fi and serious, but that's more of a tone shift than a genre shift.

If you follow the development of the story in the supplementary History of the Lord of the Rings volumes, it soon becomes clear that this was actually Mid Development Genre Shift, as Tolkien kept trying to go forward with the light and humorous tone and the plot kept getting away from him. He kept having to rewrite and revise, and each time he did, the tone shifted darker (although the early concept of "Trotter" (=Strider) as a Hobbit with wooden feet was pretty dark to start out with). Finally he gave up and started letting the characters and the story tell him what he was going to write.