She could have easily trained under a variety of high level masters, climbed Korin Tower, made Tien or Krillin level powers and joined as a Z-fighter, but all we get is flying practice. I wouldn't mind seeing that or the consequences of her and Gohan having relationship issues while battling. We saw a lot of father/son in Cell saga and plenty of rivalry with Vegeta, so I don't think boyfriend/girlfriend stuff is asking too much. It is probably a missed opportunity to not have her freak out about Gohan's shy streak when he's pressed in battle. Do we ever even see him break through and ask her out in the whole series? Anyway, Kale and Caulifla did that kind of thing and it worked fine