Thanks for replies.
About colors: I'd like to make Gadget colorful and everything, but there's a dilemma.
There are basically 2 colors and they aren't really changable
A. Simple red->blue replacement in palette 0 does look shitty and definitely affects the 2nd player, crates and other objects.
B. Can't rely on palettes 1,2,3 Changing them will also require redrawing some of the enemies (and most likely blue Zipper).
C. To add a color to the character I have to use overlays. I haven't learned it yet how to change the sprites' structures + I need spaces in both PRG and CHR
I think it would also cost minus one character

That's why I posted it here. Any useful tip/ advice/ help would be appreciated
I agree with you, Gadget's colors sre not good, but the graphics are pretty good, Of you want to do new levels and other stuff I can help you.
Thanks! Yes, I've been thinking about changing some physics and level re-design
By the way, maybe this method will help in releasing a palette