Things that need to stop being in kid shows.
"I can’t lose to a girl"
"I can’t believe I lost to a girl"
"you let a girl beat you"
If you keep showing these types of mindsets to kids they’re going to think they should think that way as well.
If you HAVE to do it, go the Avatar/Korra route, where the show itself shows that this mindset is wrong and forces the person who thinks like that to learn, adapt, suck it up and learn to respect the abilities of women and girls.