Edit: Nevermind, it seems I was wrong. Sorry for the inconvienience!
http://www.youtube.com/watch?v=7CTPmr7MkG4
Look at around 0:55-0:58. It smacks Fox down fairly hard, and at 0%, to boot. It looks like it has to connect at the peak of his backflip. I hope this hasnt been mentioned yet, I didnt see it when I searched for "spike" or "upsmash spike".
http://www.youtube.com/watch?v=7CTPmr7MkG4
Look at around 0:55-0:58. It smacks Fox down fairly hard, and at 0%, to boot. It looks like it has to connect at the peak of his backflip. I hope this hasnt been mentioned yet, I didnt see it when I searched for "spike" or "upsmash spike".