new models and such are only cosmetic changes, if you will.
you replace old characters' models/skins/sounds/whatever with other models/yaddayaddah, so you can see the custom model you have installed, but people online will still see the model they have installed with the same name.
suppose you download a gogeta model and replace your old goku model with it, everyone playing goku online will look like gogeta to you and vice versa.