This is a pretty cool animation for being done in one hour. A few things to say. I'll be reviewing this animation from two lenses, looking at it as a one hour project and then as a complete one, regardless of time. This sounds harsh, but a lot of things in your animation that I didn't like could have been because of the time limit or a mistake I beleive you made, and sorting the two out will take way too long, so I'm going to express every little nitpick with your work. Please keep in mind this is just to be through, not be mean. It's really likely a lot of these are just because of the time limit. However, I rated it through the lens of an animation regardless of how long it took to make, because those are to tell everyone whether the animation is worth their time or not, and how much they enjoy the animation won't really be affected by how much time you put into it. Cool, let's move on.
The sound effects are few and far in between, and when they do come, it's almost jarring. I read in another comment that this was because of time constraints, but I beleive if that was the case, you should have removed them altogether. Small nitpick, moving on.
The animation in general has a lot of weird places where I feel there should be extra frames. The animation in general lacks a lot of transition of frames, and for that reason it feels really strange to watch. The motion isn't fluid. A lot of the animations are cool, I like the spinning animation the robot does, and the sword slash animation. They're pretty cool. But transitioning between those different moves needs more work. It's jarring to see the monster just suddenly turn into a ball out of nowhere and start spinning. Same for a lot of different moves. There are very little transition frames to any given animation, making the whole thing feel less fluid. This may have been a time constraint, I don't know. Moving on...
The fight scene that takes place in the animation is extremely hard to follow. First we sit staring at the fighters for a few seconds then wait what, a title card or something appeared but wait no it dissapeared and the monster turned into a ball, but wait there's a pink ball too! I found it really hard to follow along
with the animation because the fight choreography and camerawork is just all over the place. Part of it is just the lack of transition frames I mentioned earlier, but there's a lot more to it. One scene that made this immediatley obvious was the scene where the monster turned into a spinning ball for the first time. A pink ball went to meet it, and the first four times I watched the animation I couldn't tell what that was all about. There was something in the background bu the scene went by too fast to check. Only when I ignored the main action and looked at only the background image could I figure it out. Not only is this harder to read, this placement of actions all but garuntees that the viewer will see the foreground before the background. This means they will see the pink ball that was thrown before they know how and why it got there. To fix this, you could just add the animation of him throwing the ball in another scene beforehand. You already have the animation and the background art, after all. But this is only the worst case. Characters whip out new abilites all the time, and while most of them amount to slashy lazer swords, they're still hard to differentiate in an animation moving this fast. The blue character keeps coming out of different edges of the screen and ambushing us, when the white lights start flashing, almost nothing is readable. The cuts move by too fast. In any standard movie, usually the hold the shot a few frames longer then necessary to emphasize the cut in a battle scene. Check out avenger's infinity war for an example of this. Now obviously comparing a tiny newgrounds animation to a live action big budget superhero movie isn't the best choice, but both operate on the same principles. Since in infinity war, all the character's moves are established, the cuts go on for a little too long, and the camerawork is clean, the action scenes in that movie are fun to watch. This one just isn't that fun.
Well that's it really. Hope you read this through to the end, most people don't. Despite all I've said, please beleive that I do in fact really like your animation. The slashy lazer swords are cool, the different moves and stuff are fun once you've watched the animation enough to know what they are, and looking at this and thinking it was done in one hour just blows my mind. It was fun writing this review, so, hope ya had fun reading it.