1) Make her a Bakugo/Todoroki level hero stdent. Either let her quirk be as broken as possible (=remove her daily limit), or make her a keikakku master who can asspull her way out of everything. That's how a worthy rival should be.
2) Give her a cooler base weapon to create on the spot and specialize in for close combat, why not a fancy naginata? A kanabo would be cool too.
3) ultimate attack consists of something cool and flashy like spamming fancy canons and fancy cannonballs with art nouveau engraving
4) let her keep her modest personality, and be genuinely anxious while watching her keikakus work like charms instead of being sumg and going "kukukuku" the whole time like a classic keikakku master. It gives her character. That's often the way actual star students tend to be too.
5) new character design, replace her belt and bookshelf with a mini ipad stuck on a garter on her thigh, make her outfit more unmistakably american and wonder woman like (add stars, star sprangled fabric, a crown and shit), change her haircut. Giving her a full body suit with zippers she can unzip at need and make her more and more naked as the fight goes on would be nice too.
6) make her creation more visually interesting than just "lel, transmutation", give her a signature gesture when she does it