I just have very little experience spriting. I have done some stuff before, and it wasn't TERRIBLE, but... I'll have to practice, and if nothing else I can at least try to help out by doing frames of animation that can be sprited over. I mainly just have a lot of ideas, most of which I don't think are currently in progress, but I could be wrong. To save you lots of headaches reading, I'll spoiler tag each section to keep the walls of text to an absolute minimum, since I have a tendency to go on and on.
[Spoiler=
Yaridovich]
The personal bane of my existence from Super Mario RPG, as well as what I consider to be the coolest of Smithy's Gang. This one is probably one of the harder ones I've thought of trying, but I just have a lot of fun ideas for him.
Overworld Aspects:
-Poses for Toad disguises (walking, talking, transforming into Yaridovich, etc)
-Basic poses (Standing, talking, maybe walking)
-A pose where he's shrouded in his cape and then whips it out of the way dramatically
-A spear stabbing animation (I just imagine it'd be funny if he offered to heal you a la Rubicante from FFIV, only to go "PSYCHE!" and stab at you, forcing you to jump to avoid taking damage or getting stunned)
Battle Aspects:
-Possibly battle sprites for the Toad disguises?
-Pinwheel on the back of his head spins before he attacks with his spear to determine which Bro he stabs (Left Mario, right Luigi)
-Seperate animations for standard attacks and idle poses for whether he has just his regular spear out, or whether he's using his head as the spear's tip (If his head is regular, he can't be jumped on, if it's on his spear, he can get jumped on).
-Phasing into two Yaridoviches, as well as splitting into Drillbits, and perhaps back the other way.
-Heat Stone: Could probably just be like the Mystery Meteor from the actual M&L3, only without the question mark. Essentially, he'd summon it down, and the bros take turns deflecting it back at him.. either he'd get hit each time, or block and block until either the player or Yaridovich messed up and took damage. Also, can only perform when his head is on straight
-Water Blast: Kind of a big liberty here changing the nature of this attack. Instead of being small explosions that lead to a big explosion, picture this: With his head on the end of his spear, he stabs the spear (and in effect his head) into the ground. Then the spear head would repeatedly burst out of the ground in a motion forward over and over down the center of the screen, and would approach one of the bros depending on which way his face is facing (If you can see his eyes, it aims for Luigi, if not, for Mario). I probably won't do this one because it's not an actual attack he does, but it is interesting, and I would do it if someone actually wanted to see it... It's hard to describe without a sketch to show it though.
-Possible alternate palettes, such as Machine Made, X battle Palette, and maybe a rust palette (remember how Ton's RPG boss sheets sometimes featured rusty alternate palettes?). Another fun idea is the inclusion of an Overheated sheet, like if he fought Bowser and got burned with fire to the point that he glowed red. Just an idea... Better yet, what if that set his cape on fire?

[/spoiler]
[Spoiler=
Jinx:]
Another Super Mario RPG relic of... tiny proportions. A really, really small character, but I could make up for his smallness with an abundance of fun animations.

[/spoiler]
Thought about Culex, but he's being made already probably.
[Spoiler=
Booster: ]
One of my favorite characters from SMRPG... Okay, I think I've realized by now that most of my ideas are for characters from the original Mario RPG, so... yeah. xD Not much in the way of ideas for this guy, though, other than ideas for how to animate him that's really just in my head and is too difficult to describe in text. However, I assume the list of attacks I would have for him would be punching, riding his locomotive, calling out Snifits, throwing bombs, and maybe biting... he just has such big chompers! [/spoiler]
Those are all the ones I can think of at the moment, I know I had more ideas. In reality, I doubt I'd even get to finish one any time soon though... I will get to START some though, after school is over. Then I'll see if I can actually manage to help. xD