Over the years, I've done 3 gig ones and one on-line one. IME if there are "judges" they are mostly window dressing, and the winner will always be the band that turns up with the biggest number of vocal fans. So as long as your daughter's band are reasonably competent what they really need to do to win is muster their every single one of their friends and family to come along and make a lot of noise ideally whilst wearing T-shirts for their band.
Having said that only one of the four I did was absolutely pointless, and that was the one I did with the band that went on to be the most successful of all the bands I've played in, although back when we entered it was still early days, and we hadn't quite found our performance style or image. It was also the only one where the sound was uniformly pretty awful throughout the evening. The other two gig-based competitions were at decent venues with excellent PA systems.
For the other three, one got me a gig on the main stage at Rock City, and the other two resulted in my band being on fairly high-profile compilation albums.
The on-line competition was interesting, because it was to a much larger extent based on non-partisan voting, and as a contestant you also had to rate the other bands in order to boost the chances of your band being heard and therefore attracting votes. When the competition finished my band came 8th overall (out of over 1000 entries from all over the world) and came top in the Dance Music sub-category. As a result we were included on the best-of compilation CD which picked us up a lot of new fans and had several management companies interested in the band.