Sophie theory. The poor gal has been shoved almost completely aside in this one, relegated to just a couple of scenes where she doesn't do anything important. I guess, technically, she's not in high school yet where this one is set, so it would be hard to use her more. Still, she should be about the same age that her older sister was in Part 1, meaning her mom and grandma, one would think, would be fighting over whether she should start training as well. Poor Sophie.
One thing that hasn't changed since the last two movies: Marnie is still a massive screw-up. In this one, she accidentally bets her entire family's magic powers that humans will be able to live with Halloweentown monsters without freaking out. What? For some reason, since opening the portal between the two worlds permanently in Part 2, she has a bee in her bonnet about getting both worlds to live together. Why? Last time in the distant past, as they told us in Part 1, humans were such meanies that they drove the monsters to make their own dimension -- Halloweentown -- to escape.
This is just the irrational X-Men thing again. Both Professor X and the Cromwells are so delusional in their hippy "let's all hold hands and dance together" crap that they want a collection of super-powered entities to invade the human world. Humans should be freaking out about this. The Halloweentown witches have, what appears to be, unlimited power to alter reality. How are these folks not going to take over the human world?
Even if they were -- very, very improbably -- all nice, they're still super-powered. Construction businesses? Gone. The witches have demonstrated they can build structures with a wave of the hand. Anesthesiologists: out of job. The witches can knock people out with magic. Airline travel? Gone: the witches can fly people on brooms. Could we humans do anything about this? Nope, the witches have a time travel spell and can prevent anything we do against them before it even happens. This is terrifying.
Sorry, as a human, I'm firmly on the side of "bad guy" Dalloway in this film who wants to close the portal forever. I'd like my daughters to grow up in a world with more career options than "Igor" or "Witch's Familiar."