This has many undertale au body parts that my friend wanted me to mix and match
any suggestions for a new drawing just ask im free for ideas
Okay, so you commit many pixel arts issues that every new in this area do.
I see many colors from the horns which only take a new color and you put down, down and down. The jacket have different colors and this outline doens't help in nothing, it's divide the parts the arms from the torso for no reason, otherwise the jacket create a great slave between the arms, the jacket'arms doens't follow the construction of an arm and there is no light source, that why your pixel art seems flat, you need define a light source to show where the lights hit and where the shadow hits and then create shape using the colors.
The best thing you can do is lower your colors numbers, define a light source and then fix the arms, these are the easy things that you can do it and then submit again.