For ZSS, it sounds like the pcs/pac is the problem. Does ZSS freeze the game when you try to start a match as her via holding shield? Try re-saving them in Brawlbox.
As for Wario, I'm not sure what the problem is here.
Well about ZSS, when I am as Samus--I would get the FS and try to become ZSS it crashes. Even if I do the taunt during battle to transform is the samething...
Huh, never thought about the one with the shield you mentioned, never tried that yet. I just tried it now and... O_O I am as her now! Wow.

Huh. At least that one about the shield trick works so I can be her. =/ Strange, it seems like I can play as ZSS w/textures if I do the shield trick but it will crash if I try to use Samus' FS or taunt. That is so crazy.
Thanks for helping me solve one bit of this problem to make playing ZSS hacked possible. XD Although doing FS or taunt to be her is still a problem. And I am not sure if re-saving could help it, I will try that one again 3 more times with the texture I made.
Yeah, the one about Wario/Wario-Man is verrrrrrrrry strange. That, I don't get. =/
Did you make sure that the PAC files are decompressed? If they're compressed, your game WILL crash.
Decompressed? Oh my gosh, I better check that out. Thanks for the tip, I will make sure these textures are not compressed.
***EDIT: Oh wow it worked! You solved my problem, thank you!

You are right, it did had to do with the Pac file having compression on it, I set None on it which is decompression and it fixed BOTH my ZSS & Wario/Wario-Man problem.

Thanks a ton. ^.^ ***