Nice to see you again my friend. Glad you're back into the spriting game. As far as these sprites go, I think they are really great.
First of all,
Skull kid - It's pretty damn good, but the first thing that comes to mind, is a deku scrub. Even though it does strongly resemble skull kid, At first glance I was sure it was a deku scrub. The hat looks great. I know skull kid's face is dark like a black mage, or a deku scrub's would be, but I think the way you have it makes it look a little too much like a deku. Maybe if the glowing eyes weren't so big? Or that little round thing in his face was gone (that, probably more then anything makes it look like a deku scrub face)
The body is decent, but when it's all pushed together so tight plus the green shades you've placed around on his arms and legs look like some kind of leaves below him. And Even with the hat on, it's still not hard to mistake it for a deku scrub, because lots of them have orange/brown leaves on their head.
The sprite itself is very good, it just needs a little more distinguishing between a deku scrub and skull kid.
Happy Mask Salesman - Looks perfect. I love how you captured his personality on his face in such a small space. The hair is really big, but then, thats how it's supposed to be. I don't really know what criticism to give you on it, other then, where is the backpack? However I think that might ruin it. This sprite is pretty well perfect. Of course there is
always something that can be improved on all work, I cant think of anything immediately. And even if he is a little to tall, or a sprite with as much character as that doesn't fit the style of normal lttp npc's it doesn't matter, because it would still fit into all the lttp tiles perfectly, and personally I prefere sprites like that with actual character int he face and body over the standard lttp anyways.
Talon - I can't really point it out, but something about him looks odd. But going over him it really looks like Talon should. It might just be because with the mask salesman you captured his face perfectly, and then on Talon it just has the same old lttp eyes with too much white in them. But thats the style. It looks good overall, and it would probably look even better 2x.
Goron - It looks pretty good at first glance. But if I really want to try and find something wrong with it, maybe the shadows above the eyes are a bit to dark? Or maybe (even though they are supposed to be low) the eyes are just a tat
too low? So there really isn't much room for a slightly noticeable mouth. Maybe the color pallet in general is a little to orange, but overall its pretty good, considering all the other gorons Ive seen
Zora - On first glance, all I can really say is, I don't like it very much. I don't wanna be an ass cause I know you spent time eon it, but I am just being honest with you. I dunno if its the way you did the colors, with the white, and then straight to darker blue around all the edges, or the size of his head, or the general look on his face, or how wide he looks in that frontward pose. It just looks kind of wacked. I wish I could give you a little more constructive criticism on how you could make it better, but I cant quite pick out what would need to be changed. It would work in a game of course, and probably easily suffice. But yeah.
Overall, they are good sprites. I'm glad to see you're working again man! Keep up the good work, I look forward to seeing more.