I'm not sure if anyone else is working on this, but I'm gonna be gone for awhile, so I'll post my notes:
Disable is working and easy to recreate; just a basic hitbox with a stun flag. As of now it's pretty unbalanced, though; it's a free fsmash even at 0% and I can't figure out how to decrease the stun time. Likely solution is to increase the lag on the move. Oh, and it needs separate air/ground mechanics so it stops halting your momentum in the air.
Teleport looks to be a little more difficult. Zelda's up-B, Sheik's up-B, Metaknight's cape, etc. are all brimming with undefineds and editing the subactions they call only affects what you can do before and after the teleport. Length, teleport time, directional capabilities, and whether or not it causes freefall are all things that we'll have to figure out by trial and error.
Confusion is probably possible by making a grab hitbox that sends the opponent very slightly up, forcing a techchase before they get out of stun. I don't know if it's possible to recreate the reflect-but-not-really-reflect effect it had on projectiles in Melee, but I think we can settle for an actual reflector if it isn't. And let's make it flip the opponents around like Mario's cape, too, just to screw with their heads. It wouldn't be Confusion without being confusing.
Shadow Ball is obvious. Aura Sphere, however, is insufficient as a strict replacement (at least for me) until I can get it to fire in that back-and-forth motion Shadow Ball had. Since the sphere is a prop and we can't edit props yet, this will have to wait.
Fthrow shouldn't be a problem to recreate.
Nair, usmash, jab (first hit), and grab all spawn hitboxes from relatively similar bones for Lucario and Mewtwo, so these should be able to be recreated without the model importer. Mewtwo's dsmash could also be theoretically recreated by using Lucario's down-angled ftilt animation and having it spawn a darkness effect.
A way we could accurately recreate Mewtwo's moveset on Lucario while still having it be transferable between the two models would be to associate all the hitboxes to a bone in the same spots on Lucario's and Mewtwo's models like the torso.
Mewtwo's standing animation should be him floating off the ground with his arms crossed. Totally badass.
On that note, making acceptable model animation is hard. I'll be able to get it done eventually, but ****ed if it won't take forever. Are there any people interested in this who are actually experienced with working with models?
Mewtwo's trophy model needs more detailed textures before we can use it as a character model. It looks out of place next to the more detailed textures on the normal characters.
General mechanics should be easy to recreate; test where Mewtwo is in relation to other characters in Melee, then use those results to come up with values for Brawl.
Until it's possible to repack BRSARs, getting rid of all of Lucario's voice SFX and having Mewtwo just go silent seems like the best method.
Mewtwo, obviously, will have to be balanced separately for vBrawl and Brawl+.
I wish Brawl had a debug mode.
Life throws bull**** at you at the worst possible times, I swear. I won't be gone indefinitely, but it'll be at least a week or two before I can get back to working on his moveset, let alone the model animations. If someone else decides to take this up in the meantime, please please don't do a half-***** job of it. Getting Mewtwo into Brawl is going to require making all the prim and polish of every other character, and this game is polished so much it shines more than a Melee Fox main.