From looking at them, I can only make some logical guesses about them and their fighting styles. (I hope all of the characters in your initial post make it in, except Ileum). Mike Z, if you are reading this, you can use these ideas if you want to.
As SteelyHawke stated above, her mask could be like what the High-class wear to ballroom affairs and other social gatherings. She could also be using it to hide her identity when she does an assassination, or it could be her trademark look in tandem with the giant gun on her arm.
As for her fighting style, I could see her being a run-n’-gun style of fighting, working from more of a distance, switching out different types of shells between a regular bullet, explosive shell, or another type of shell.
How about she talks like an adult, but it comes off all cutesy because of how young she looks.
Her sword is a prop, but she can pull out a real one from her teddy bear’s mouth and use it as a new weapon for a few seconds in a Hyper.
Fire + martial arts = Captain Falcon references like Falcon Kick and Falcon Punch?
I got nothing on this one other than maybe being like Dhalsim in that she can have stretchy, intestine arms to use for attacks and grapples.
Thorns on her legs? What if they aren’t thorns, but stingers, like on hornets and bees? Special attacks where she can kick and let, like, a stinger on her heel poison the opponent. Or her being like Marvel comic’s The Wasp, in which she can grow wasp-like wings on her back and fly?