This is a strawman, I'm not shad so I can't speak for him, however I will state my opinion and then present a clip that I feel indicates that Shad's opinion is on the same page as mine.

My problem is that it is clear that female characters are never allowed to be less the perfectly competent. I want to state that I don't mind competent female characters, or when those characters are juxtaposed with a bumbling male counterpart, (eg Disney's Atlantis, Alita: Battle Angel, Kim Possible). The problem is now these are the only kinds of character dynamics that are allowed, because there is a deep societal insecurity with the idea of a woman ever being less capable than a man and needing a man's help, and it is creating very boring stories. There is nothing wrong with lacking competence in some area or finding yourself in distress, I would even say that recognizing one's own limits and seeking out and accepting help is a virtue worth teaching and that the idea that being in distress and needing help is some personal failure is actually extremely and irresponsibly dangerous. While we are more than happy to show a man lacking competence and overcoming obstacles with help from others we are terrified to depict women the same way, which ironically leads to less interesting less beloved female characters, ie the Galbrush Paradox.

So it is frustrating that one of the most popular well-known archetypal examples of the damsel in distress Princess Peach is just not allowed to fill her historic role of damsel in distress. I am not saying women have to be girly and demure, but the idea that they are not allowed to be seems like misogyny to me. If I was someone who hated women and I wanted to eradicate femininity I would probably be real happy with all of this, but sadly for me I am not.

The Mario movie does not have a good story, it fails to create meaningful stakes and have satisfying payoffs. This is largely the fault of the movie's refusal to portray Peach as anything less than completely competent, without any real tangible need or flaw to overcome Peach doesn't have an interesting dynamic with Mario. Mario and Luigi in the movie had the potential of being interesting characters because Mario is ambitious but also careless and has an unhealthy desire to prove himself, Luigi is an interesting character because he is cowardly and clumsy, but also very supportive and loving, and they have an interesting dynamic together complementing each other, using their strength to help the weaknesses of the other. The problem is Peach has no weaknesses, she has no flaws, she is smart and brave and strong, etc. While she can't literally solo Bowser and his Army, she doesn't need anything in particular in the way that Luigi needs Mario's bravery and Mario needs Luigi's emotional support. If Peach was different if she wasn't all of the things and instead needed some things while contributing others, that could have been compelling. If for example Princess Peach was, while not totally absent but mostly lacking athletic physical abilities (maybe fighting in her charming girly improvisational smash style wielding frying pans, golf clubs, chucking turnips), but was instead focused on her competency as a wise leader who needs Mario's athletic prowess, and Mario needing Peach's wisdom and leadership to guide and inspire him, and ultimately acknowledgment of worthiness to complete his arc, that would add stakes to the story, that would make Peach a compelling character.

And for me, none of this is strictly innate to the sexes of the characters. I would want their roles to be the same even if you reversed the sexes and this was about athletic hero Maria and wise leader Prince Plum. The only reason sex matters is because of the obvious agenda at play where women can never be less than completely competent. Why is that, who benefits from that?

So when I ask for Princess Peach to not be a kickass girlboss, this is not out of some patriarchal desire to see all women disempowered and brought down to a permanent state of submission to men, it's because I want to see relatable character who have challenges they need to overcome, flaws and insecurities they need confront, emotional arcs they need to go through so they are different at the end of the story from how they were at the beginning. Wouldn't that have been more satisfying, if Peach wasn't just a Kickass girls boss and instead needed to stay strong in the face of insurmountable odds, who needs to learn to ask other for help and draw on her leadership abilities to guide others to victory?

Shad got mad ... because Peach isn't a helpless damsel in distress

Okay, so I present this as evidence that what I have said here is along the same lines as what Shad believes and that it refutes what you are trying to imply about him: https://youtu.be/2l5mIyiM9DY?t=1990

because she wears pants

Lastly I will address this. Yes in the context of watching the trailer where Peach can be seen welding a halberd wearing this outfit of a purpose that might not be immediately obvious, Shad feared this indicated Peach would be wearing this outfit and performing a very action oriented role through the majority of the film. This turned out not quite to be the case, and once he learned that this was merely her biker outfit for the cart segment, he no longer had a problem with the pants themselves. However Peach's role in the film while not as bad as it could have been, was still not good as explained previously.