You can have pac files of Samus and ZSS, but you need to look in Brawlbox that the pcs file needs to be compressed and the pac file needs to be uncompressed:
If you see the image in the spoiler, for the pac files, they need to have the "compression" line set to "None", of that form you can prevent Samus/ZSS, Wario/Warioman, Bowser/Giga Bowser and the Pokemon Trainer and his pokemon of freezing when they transform in their final smash in the multiplayer mode.
This applies too, to all characters in the solo modes, to prevent them to freeze in the Subspace Emissary or when you fight the Team Battles of the Classic mode.