Yoda was visibly pushed back by Dooku's lightning, and Dooku's lightning feats are <<< Nyriss', so she breaks his tutaminis and burns him in Force.
As for dueling, her ability to dance around fodder a totally at prime Meetra and the MVP Scourge who Sidious would have trouble with, means she handily bests him in sabers.
All out? Put it together.
Spoiler:
Seriously? Tyranus murks Nyriss, so Yoda sh!ts on her mercilessly