Hi there Sersch! Welcome to Pixelation.
That's a charming band of characters you have there!
I hope you don't mind that I took the time to make an edit of your little robot friend!

Since all his colors are very close in both hue and value details like his arms are lost. If you have a player with a dark or poorly calibrated monitor they would not be able to see what is going on. In fact your 4 darkest colors are all similar enough that they're pretty much indistinguishable. To remedy this I brought the color count down from 18 to 10. The reason to utilize a small palette for a sprite this size is so that you have more control over every pixel and you don't end up using the wrong colors on the wrong objects. I also tried to bring in more highlights, not only to better illustrate the texture of metal but also to contrast the different sections, to make the limbs stand out next to the body. You've used your most dark color only in his visor and parts of the "chimney" if you instead use that color in the entire sprite it will give it more balance and your colors will pop more as they contrast to the dark.
Still the colors of the limbs are still quite close to the ones on the body, similar earthly tones. So in my next version I tinted the body more towards a metallic blue and the limbs to more of an orange which are complementary colors.
Now the different sections pop and the sprite can be clearly read, this will also help it standout next to dark and busy backgrounds. In this version I also got the color count down to 7, which might be a bit frugal. But I like to keep it low.
Another thing I tried to do throughout my edit was to think more in "pixel clusters" what is meant by that is try to minimize the use of single pixels or outlines and instead try to think as much as possible in shapes that fit together, sort of like Tetris blocks! This help separate the forms in the sprite which is especially important at this size!
Hope this feedback is of help. Cheers!

I would also make the tengu's nose wobble a whole lot more! A nose that long is an asset!