This brings me back to the days when sprite battles were a big thing.

Not bad, I always liked these kinds of fantasy battle sprite animations and this one was pretty decent.
The biggest thing that I think could've been done better is that the Doomguy sprite was pretty bland and blurry, which looks especially weird when juxtaposed with Samus's brightly colored armour and higher quality sprite that contrasts really well with the scenery. I'm assuming you got the sprites from somewhere online? In the future I'd recommend collaborating with a specific pixel artist to get your assets custom made, that way even if they're not the highest possible quality, they'll still look consistent next to one another.

Overall, as far as first submissions go, this one was pretty good, and I hope you make more of these in the future.
Also, I saw on your profile that you just joined today, so welcome to Newgrounds! Keep up with the animation and keep improving and I'm sure you'll do well here.