What are the means to reduce the weight of a Pcs file, or a pac file?

[Psycho Philia]

I want to make an import character, very particular. In fact I want to place Marth on Zelda, but my problem is that it seems the files of Zelda are too big when I put Marth model (with 33 added bones or it won't match Zelda's number of bones) and Marth's textures. So is there a way to reduce the weight of the pcs file and the pac file? Can I disable for example bones that are not useful for me so that I gain weight and I'm hopefully able to make marth work on Zelda? Thank you.