Hey there, I will be replying here. Hope you don't mind. 🤔
Yeah I knew about editing backgrounds in EpicEdit as I tinkered with changing some colors a bit in my own hack. I just want to know how would I be able to get a png of a background from MKSC and fit it into SMK's 8x8 tiles while using the limited colors
There's no tool that will automate that. Instead of looking into full rips PNGs of the backgrounds, download a MKSC ROM and fire it up on Visual Boy advance. IIRC, the tools that emulator has lets you see the background graphics that are loaded in, and export them into a png file.
Since it only exports the actual graphics (and not the runtime placement of them), you can then begin sectioning the pieces you need. Since SMK is limited, you will have to edit them manually with any image manipulation tool and confine them between the available space the game has, along with making sacrifices in color details too.
I remember looking into other BGs from that game I could use here, but most of the assets are bigger than 24 px (and even the small ones are in that height), so you will surely need to manually scale them down, break them into pieces of 8x8 and only use 3 colors so they keep the same dimensions the MKSC background had.
It's a long process, but basically that covers it if you want to attempt porting MKSC backgrounds into SMK.
My other concern if you are trying to import the backgrounds for MKSC to SMK, remember that SMK only has 8 themes, so not sure how things like Cheese Land or Ribbon road will fit in 🤔
Each background layer in theory has 1 page dedicated to the palette (with 4 unique palettes, each of 3 colors for each BG), but I noted that Epic Edit lets you use the colors from the page next after their original palette page. While this looks great in paper as you could indeed cram more objects with different colors into a SMK theme, the colors from the next palette pages are used somewhere else (I don't remember what items/objects/HUD/sprite did use them)
TL;DR, you need to manually downscale and re-sprite the backgrounds to fit into SMK background space.
Hope this info helps in give you a general idea on how to change the BGs 🙂