It totally depends on the game. For Brawl, use BrawlBox, it should let you replace most textures and save a new .pac or .pcs: http://www.smashboards.com/showthread.php?t=238861&
Main Laptop:
Dell XPS 17
i7 2720QM @ 2.2GHz
8GB DDR3 RAM
Nvidia GeForce GT 555M
Windows 7 64-bit
Dell XPS 17
i7 2720QM @ 2.2GHz
8GB DDR3 RAM
Nvidia GeForce GT 555M
Windows 7 64-bit
