I think the foundation you have going feels fluid and fun! The characters are charming and animate well in-game. However, because each of the characters' movelists are so short, the characters struggle to feel interesting or different in a significant way. Therefore, despite the system mechanics in place lending to cool, flashy combos, the extremely limited number of special moves per character make each character feel one note. In the future, I would focus on adding fewer characters but instead fleshing out the characters currently there!
Keep up the good work!