Well, for the arms, I was going for a lanky look so I figured the thin look would fit better, but I can make them a bit thicker.
As for sheets and what I'm using them for, they are for the game I've been spriting for "Mushroom Patrol: Midas Machine". As of right now they may not be used but I have 2 plans for them. The first is to have a castle level that works like the final level in SMW in which you have 2 sets of 4 doors to pick. Each door will have 1 of the 7 koopalings (plus Jr in one of them) and as you go through, they will give you trouble in some way (usually by dropping objects from above that interact with you in different ways). I also want to have them show up as bosses in and after game bonus world.
As for if I'm sheeting it, well, I guess I've already answered that, although most of them won't fight in the traditional means (shooting from wand, jumping, ect.). Some will fight from in personalized Koopa Clown Cars and what not. This is for 2 reasons. First is because I don't feel like fully animating all of them, especially since I lost most of the pieces. Second is because I want to use various game gimmicks as part of the fight, so the traditional fight styles wouldn't work. So yeah, they'll have a sheet, but not a traditional one.
K, I made the hair only have 3 locks and have them placed as seen in the official art (not sure if it looks any better. For whatever reason, his hair is tricky as hell), made the eye rings lighter, and I made the arms slightly thicker. I don't want to make them much thicker than they are as of right now though as I think it will make him look more muscle based.