Something tells me that the star at the tip of the luxray's tail is... Well, just a star. It seems common that a few of luxray (and it's other evos) get this sticker on them...
I don't think the devs at Nintendo gave any Pokemon anything like a tail maw to any Pokemon beside mawile and that giraffe one with small orb-like head for a tail.
Correct me if I'm wrong though~