I think I know what the probem is.....
Riivolution replace the files in a different way.....
Example:
-Gecko os replace the select character screen with the menu2 folder(sc_selcharater_en)
-Riivolution replace it with the select character screen with the sytem folder(common5.pac)
You may notice that some character's motion files are in the common.pac(Zss, Samus, Sheik and Zelda motions), common4.pac(Kirby, GBowser, Bowser and Ivysaur motions) and the common5.pac(Charizard and Squirte motion files, sc_selcharacter2_en, sc_selcharacter_en and sc_selmap_en)
This is the way how you should replace the motion file for Zss...
I hope this will help you...^^
Hey, that worked

Although you can also replace the sc_selcharacter_en.pac using Riivolution (I did so).
EDIT: So I started up the game using Riivolution and even before the strap loader appeared it froze (with the annoying beep sound), is this because I'm using a common_en.pac file from the US Brawl Disc (I couldn't find the system folder in the Pal-data partition so I thought they were the same...