I don't get what you mean. Fully customizable moves or fully customizable move-SETS? What i mean is the variations of each move the character has (like we saw in the video with Mario, regular fireball, fast and straight fireball, large and slow fireball etc.). There is 4, and only 4 (1 default + 3 predetermined variations) variations of each special. Easily accessable and visible. Open menu, pick the variant for each special you want, and roll. If you want a reference to other fighting games, its like having "Character X" A and "Character X" B, only you can also leave 3 specials default and only change the sidespecial.
If you mean that by "build your own moveset" and not "i can exchange my ability for whatever ability i want" then that would be it. But in the later case no. You simply have different variations of the standard attack, EXCEPT for Palutena and Mii Fighters, whose specials do greatly differ from each other.
Example for "normal" characters: Mario and his fireballs.
Example for Palutena: Up special (Teleport, or Jump-Glide, or...)
If you have any more questions to this PM me, so we can get back to the topic at hand: Mewtwo.