Unfortunately I don't have the equipment for videos... but here's an explanation of how to do it. It's rather simple now that BrawlBox is so powerful.
First, open up the FitCharMotionEtc.pac file you want to take a move from. Under FitCharMotion, then Animation Data, you'll find usually 3-4 Anm dropdowns. Find the animation you want take in the first of these, and right-click and export, saving the file somewhere. Then do the same for any other instance of the animation you can find in Animation Data.
Then you open up the FitCharMotionEtc.pac file for the character you want to give the move to, and find the corresponding animations in the same locations. Right-click and replace, then save when you're all done! And that's it.