Few Mark Spothound sprites I made right after finishing fat Zed scenes and realizing that he has to be the main character instead of Zed. The sprites show few different stances, walking, swimming, death animation, idle stand, getting hurt, crouching and also a bone projectile (the bone is supposed to spin faster, I just had to make it follow the speed of character animations here), still need to do some more for jumping, rope/ladder climbing and attacking.
In fact, I actually did NES sprite for Mark many months before May but it was just one still image which required a couple of tweaks and also a more humble color palette that would fit NES limitation and I had to think hard about it.

Picking the right palette was a tricky task. Just like Zed, Mark is a pretty colorful character and too many of his colors are essential. Like, he can't be a dalmatian without black and white, his snout just has to be red, his nose and eyes are yellow and his purple right ear is another element which defines his unique look.

However, basic NES sprites allow only three color palettes and that's a pretty harsh limitation for colorful characters like this. Of course there's some ways around it, NES characters are constructed of 8x8 or 8x16 blocks (depending on what graphic mode was chosen for the game) and you can assign a different palette for every each block, this is how we have main character in Contra for example wearing blue pants but having red palette for the shirtless upper body and it was a very common thing.

Another way is more complex, most notable in Mega Man and Battletoads which use hovering overlay sprite for extra detail. The downside of the first method is that sprite blocks are rectangular boxes so by changing palettes you're risking to make the border between two color schemes look too obvious. Meanwhile, Mega Man needed different colors for a circular shaped face and Battletoads had those complex shaped yellow parts, there's no way to do it properly by changing palette to just a whole sprite block. And that's where sprite overlay comes in handy. Mega Man's body uses a three color blue palette for body and there's a separate sprite with a beige-white-black palette for the face. Same with Battletoads, they use green-black palette for the body and yellow-white for white details and eyes. You can check out this sprite sheet to see by yourself what I mean:
https://www.spriters-resource.com/n.....s/sheet/33456/
But this method has its own downside as well. NES has strict limits for how many sprites can appear on one horizontal line or generally on screen. The limit is 8 sprite blocks on a horizontal line and 64 sprite blocks onscreen so a single excessive sprite can be crucial. Violating the first limit causes the notorious flickering NES is known for, violating the second limit causes flickering as well but also can lead to slowdowns so it was preferable to avoid such violations and not go overboard with character sizes and amount of stuff going on simultaneously.
Now look at Battletoads characters and Mega Man, they are 3 sprite blocks wide and, unlike simpler recoloring method, the extra face detail adds one extra sprite on top of it which means the face zone has 4 sprite blocks on one horizontal line out of 8 and you can add only 4 more for enemies without causing flickering. Flickering is not a sin, both Mega Man and Battletoads are good games and they had a lot of it but it didn't stop them from adding big enemies but you still have to think about minimizing it as much as possible. This is actually the reason why NES beat em ups with big sprites like Double Dragon, Batman Returns or TMNT were limiting the number of enemies you fight simultaneously to 2-3.
There's another downside of having a colorful main character who uses more than one palette. NES can change color palettes on the fly of course but yet it can display only 4 three-color sprite palettes simultaneously on one screen. And since main character is the only sprite which is ALWAYS onscreen and needs its design to be consistent, every palette you pick for the main character becomes fixed for entire game and cannot be changed. Going back to Battletoads, you can notice how many enemies use green or yellow palette because these are the palettes used by toads so you have only two interchangeable palettes left for enemies and other sprite-based elements. So, picking just one palette for the main character was beneficial at how much flexible the rest of the sprite color schemes can be.

With that knowledge in mind I realized that I need to select just one uniform palette for Mark and sacrifice his color variety for the sake of convenience as none of those two methods can't be used efficiently. Mark requires precise coloring so changing a palette for a sprite block won't work and all the details that require different colors are too spread apart from each other so it can't be fixed with just one sprite and wasting too many sprites just for tiny details is too irrational.
That's how I came up with this palette which I see as the only best compromise. This crimson tone is reddish enough to match Mark's snout color properly and purplish enough to look fine on his ear which is supposed to be purple and I picked the lightest yellow as a middle ground substitute for all the white and yellow details. It's yellow enough to look alright on Mark's nose and light enough to make him look like a dalmatian. I think it looks good and can be considered an efficient sprite design.

Well, that's quite a lot of info to just tell about color choice but I hope it was still interesting for you to learn a bit more about how graphical limitations conditioned game design on NES.