Oh k, let's get straight to the point.
Your animation is exactly very fluid. Everything moves, but it isn't like fluid animation we see everyday. The plot of the flash was very obvious, he did cause some "havoc", if you can call that havoc really. To be honest I was expecting a run off from the Dad's series. Destruction wise anyway. Hmm, the detailing of the flash overall was not too impressive, they were all just plain lookin' and hell I didn't notice much in the background since you were probably more focused on your main character itself, color wise, detailing of objects, etc. Though the main character doesn't even look that interesting to me.
I feel like this is an idea in progress, if it is, then I feel like this can grow after much practice with future flashes and that maybe this can be a hit with Newgrounds. You may never know. I was hoping for more random events to happen but it did look like Happyman did really know what he was doing thus he wasn't exactly oblivious.