There are literally few characters who could win against her in a fight, and there are only about three:
1. Any osmosis jones character, too microscopic to see, and wins before the fight even starts by essentially messing up the body's systems.
2. Scud the disposable assassin, literally designed to kill, and dodges bullets faster than sonic can.
3. The most powerful character in all of fiction:.... SPORTACUS FROM LAZYTOWN