She could easily have been near their battle power in their Base forms, and altered her efforts throughout the tournament while she was fighting people who were on par with a human. Trunks had no problem doing this instantaneously and neither would she.
The entire point of her even being at the tournament was to try and win the prize money. But she had to do so without killing the other fighters, therefore; it is heavily implied that she was suppressed, and even then, she was capable of dodging an off-guard Chi attack.
Additionally, the kids had no idea how powerful she was because they can't sense her Chi, so their remarks of suppressing their Chi attack so they wouldn't kill her are based off an inconclusive power estimate that is other-wise, completely inaccurate. Because they are unable to gain the upper-hand physically, this leads me to ascertain that they aren't as powerful as people intend them to be.