>>2535964It's possible that the motion isn't creating enough 'motion' for the breasts to move on their own compared to when you jiggle the model manually, you can open the model in pmxe, look in the rigid body tab for the one corresponding to the breasts and edit the physics value to suit your needs.
As for the clothes if it's a R18 model, when the model is selected in MMD, you get access to the 4 morph categories at the bottom, usually the bottom right one has the morph sliders that make clothes disappear.
If you want to create these morphs yourself, open the model in PMXE, go to the Material tab, select the parts you want to to create the morph for, then right click > Copy Index, now go to the Morph tab, right click the list > New > Material, select your new morph (bottom of the list), in the white space on the right, right click > Copy Index to paste the references of the parts you chose in the Material tab, then click the Edit button and fill the boxes it like pic related, it will basically multiply the opacity of the material by 0, making it 0 and therefore transparent when you use the morph. You can test it out in the Transform view.
Fell free to ask if you need help.