I play the whole time Ribbon Girl and i think she is good but she has some weaknesses. Her Arms are her weakness. No distance and no curve, only straightforwatd. If you fight against her, keep distance.
Every arm has basically the same range from what I can tell. Also her Slapamander is good at curving. Literally every good Ribbon Girl player I've faced uses the same set-up of Thunder Glove + Slapamander infact.