Fluid animation, solid homage to the works that inspired you with a terrific eye for nuance style. Color me super impressed.
Ok, I've watched this several times now and I noticed something that could easily go unnoticed. The last change before he goes back to normal is different every time I watch this. Amazing job, I was going to give you 10/10 already but that little detail just sealed the deal.
I have to say I especially liked the Scott Pilgrim reference. Anyway, how about Pokemon? I think it would be awesome to see you running around as a Pikachu or a Squirtle or something.
Do one of...
Various animes, like Rurouni Kenshin, Bleach, Naruto, Highschool of the Dead *lol you could have fun with THAT one...* Hellsing, etc. That could be a "DVD" or "Manga" that turns him into the various types when pages are turned, or scenes skipped... Awesome flash dude. Just puttin that up there too.
That was awesome, and a great testament to your flash skill.
Also, since you've done PowerPuff Girls, and Foster's is in the trailer for the extended version, why not do that other currently famous cartoon that Lauren Faust did art for. I'm of course talking My Little Pony: Friendship is Magic.