It seems you're not working on it anymore. Can you at least give us a download of what you did so far, please ? You already did more than any of the other texture packs I have tried. Your pack is really the best. Please.
I really thought Teenage Mutant Ninja Turtles when I saw this. Welp that's probably where they got the idea from, lol The yellow one on the left looks sort of derpy from the older version, you did an excellent job on renewing them !
"Dude! We look awesome!" "I know, right? They should totally put us in a new game! It's like nobody remembers us anymore!" "Dude, what about Super Mario Bros Z?" "Man, I know it's totally rightous, but I mean nobody at Nintendo remembers us." "Are you kidding?! I still have a chip in my shell from those fights!" "Yeah, and I'm tired of them making me look like an idiot." "Dude, you were holding that totally rightous technology upside down when Alvin came to ask us for ideas." "Yes, but in the game, I am actually the "rightously epic techno genius" at the castle. Remember who rigged that trap for him?" "Yeah, man. I also remember you were the one who hooked him up with that Bob-omb babe that helped him beat us." "Oh ho ho! Yellow got burned!"
Pretty awesome renditions! Like others have said, though, you need to make them smile less and in turn make the cheeks look bigger. I know you're trying to make them a little original, but that can be done while still keeping correct Koopa anatomy. (I think I told you once before that I'm nearly an expert on this, haha.)
Also, please don't forget that the Koopa Bros. are larger than typical Koopas.