When setting up the Fighter Config and naming them, you don't have to use LucarioEx. You can name it anything as long as it doesn't have spaces or special characters, so entering Mewtwo or KidBuu and having ft_mewtwo.rel or ft_kidbuu.rel would work.
Hmm, well i just tried that. I'm able to pick all three lucario characters on the css, and no freezing. When i pick the third one( for mewtwo) and go to the sss I pick a stage, but when I pick a stage it doesnt load, it just stays on the picked stage as if its taking forever to load.