Well I don't know if I agree that a Yonko's crew absolutely has to have everyone be physically capable, at least to the point where I expect each and every one of them to handle the SH crew. Her crew feels kinda weird in that obviously her daughters and sons are the main heavyweights, but at the same time, it's still a family, so she can have favorites and children and what not without them necessarily all being capable of fighting, or being a part of the actual pirate crew. They could just be chilling in her territory all this time, only doing certain tasks when Big Mom asks them to. That being said, the unfortunate trend of the female characters tending not to be directly combative puts an obvious spotlight on us wanting Pudding to buck that trend. But I don't necessarily think that a Yonko can't have crew members (or in Big Mom's case, family members in addition to that) that aren't focused on combat, but rather roles such as being a doctor, treasurer, spy, etc. I mean, yea we expect them to, but it's not a 100% guaranteed thing for people with really huge crews imo
But nonetheless, though I think I'm inadvertently coming across as making excuses, you are definitely right that that is the obvious elephant in the room. As you said, hopefully she'll buck the trend even further than he already has with her character, and actually let her fight someone.