Some ideas that were posted in the original thread and some of my contributions!
Dwarf from Dwarf Fortress
Can turn into different professioned dwarfs (special attack shuffles through them) which all have special stats and attacks. (Stats: speed, damage-dealing, jumping power etc.) So Fisherdwarfs attack with a mid-range fishing rod and Miners have a Melee-pick.
The Ninja from N(+)
Basically very acrobatic, fast etc. but "dead" pretty fast.
Has a Katana and can set mines.
The Ball from Inside a Dark Forest
Can roll and bounce around. Changes its colour randomly from time to time which affects its "bouncyness". Attack is a short, extreme acceleration which can be blocked by simply "attacking it at the same time".
I'd include a "blocking system" like that anyway.
Also, we need Nethack in there. It could be a man with an @ for a head or something. I don't know. Maybe just an ASCII stage.
<big ol' picture of a clonk>
Instead of a dwarf from dwarf fortress, and a nethack character, maybe just a generic roguelike character? He would be large, stylized and animated @, and maybe he could get more powerful as he fights. He'd be relatively weak at first, but he'd be generally well-rounded in ranged and melee combat. He'd randomly be struck by a fey mood which would act like a sort of berserk status, putting him in the control of the AI, but making him more powerful. It could also possibly be a special of his.
As for the specifics of a clonk, he would have an extra helping of health, but be a little slow and clumsy. He would be a mediocre, decent at best melee fighter but could throw powerful medium-ranged flints (instant contact explosives)! His special attack could be super t-flints (bombs explode after 3 seconds, much bigger explosion.)
The list in the design document looks fantastico, except for a few like fez. He doesn't really have any implementable attacks as far as I know. It might be a bit weird to give him anything besides basic punches and kicks (chainsaw attack?

). Not that he's not awesome. Sexy hiker sounds like he would also be awkward to implement with the current control scheme. But the results would certainly be interesting!
Some ideas of my own!
Professor Lemeza (La-Mulana) - uses a whip that has farther reach than most melee weapons. A bit weak in health, but makes up for it with a pretty strong shield, a solid ranged attack (ninja stars), and good agility.
Castle Crasher (?) (Castle Crashers) - Small and sluggish, but tough and powerful in melee!
Destructivator (Destructivator) - Fast with good health. His main mode of attack is his gun which fires annoyingly quick shots horizontally that are impossible to dodge in time, but cause little damage or knockback. Weak melee attack.
I have 0 experience in creating animated sprites, but I'd be happy to give it a shot if need be.