They all use different coloring on specific sheets. The sheets by Divine Insect are using the "full" color format, while some, like Dr. Robotnik ripped by Dolphman are using a "raw" color format, while some, like the Sonic sheet for Sonic the Hedgehog (Genesis) use an odd variety of colors, which I fixed up. Also the K-T-E in Sonic 2 spritesheet is also using a variety of different colors, like the grabbing on to something frames, which are using a really light color.
I think they should all be in the raw color format.
The "raw" palette is what they should be, because even the official ports used it. (Taxman remakes, Sonic 3 & Knuckles Collection and SCD 96)
With the emulator, GENS. It has a useful VDP Viewer which shows the graphics in tiles which you can scroll to find them. Along with scrolling through each of the four palette slots. All we really need to do is get the raw palettes and give them to the sheets that are not in raw.
Basically correcting the palettes, as the white in the "full" palette on the sprites are transparent in MS-Paint.
This was the reason why I updated my rips of the S3K Badniks by giving them their correct colours and better organisation.
Yeah, I agree with you. I've already done it with the Sonic 1 Sonic Sheet, the unused Robotnik death sheet, and a few others. I haven't uploaded them yet, because I'm worried it would be like a lazy attempt, but I'm gonna try anyways.