Is it okay if I do this such as replacing movesets textures, stages, menus etc... or will it mess the hack up
for example if I replace Marth with the new Lucina PSA will it not work since its project m marth and not brawl marth .
And if I change the character selection screen will it mess up as well?
Thanks in advance.
Changing the character PSA's will typically have adverse affects and likely cause freezes unless the PSA you use has been made for use with Project M.
Stages should be fine to swap around.
Swapping out the menu will probably freeze the game unless the menu has been made with a Project M version. This is due to Project M having additional menu assets that Brawl menu screens do not have.