Yeah, Toriyama had a nasty habit of not knowing how to do anything interesting with female characters not named Bulma. Which is a shame because Videl was actually really cool I think. Seems like her moveset means I’ll have to deal with Great Saiyaman however, so I can’t be too happy about her inclusion right now. Goodness I hate that character…was basically the preface to Gohan’s slide down to jobber.
No, that’s just bad writers not knowing what to do with him. Superman is basically a demigod, and one of the most annoying things is how ridiculous writers sometimes get about forgetting that and just writing him into losing or being “challenged” in ways that ignore his previously established skills, abilities, and intelligence. Superman isn’t just an idiot farmer with flying brick powers - he’s actually extremely intelligent, and contrary to popular imagination has significant martial experience as well.
Sorry for the rant. Supes getting jobbered is a pet peeve of mine
But while a crossover would actually be kinda cool (and Superman is one of the few characters in fiction who legitimately could tangle with the cast of DBZ), it definitely won’t happen. :-p