Next to Clawdia, he's seen as the cousin of Bowser and Iggy but is never referenced again, so I drew him in actual Koopa form. Now, the reason why I chose this design is that towards the end of the Mario Movie (USA), he is turned from stupid to intelligent so I though a dignified look would fit him.
Thanks. I know, as much as the other Mario fans, didn't like the movie, but that doesn't mean Spike here should be forgettable. In fact, he only remembers Iggy and Bowser but hasn't met the rest of the Koopa family yet.