I mained Mewtwo in melee and I main lucario in brawl.
Mewtwo's teleport can be controlled, it's a lot better then extreme speed. His midair dodge is awesome and he's overall more fun to play as.
Lucario is better but if Mewtwo was in brawl and sakurai changed him to the way he should be ( He weighs 298 pounds in the pokedex, how is that light weight?). His speed should be far faster. His vB should reflect better. Even with those tweeks Mewtwo could easily pass lucario. Mewtwo's smashs feel so much more rewarding (Up smash Ftw). Overall I think Mewtwo is still greater. Plus each of Nintendo's Major series has a villain Character
(Link= Ganon, Mario= Bowser, Pokemon should have Mewtwo).
As for Lucario, his aura is awesome (although Mewtwo should be able to use aura as he learns aura sphere). His areials are fun to use and a short hop down air is a great move. He's floaty so works well in the air (not so great when trying to reach the ground). ^b is terrible but a good lucario can recover regardless of getting edgehogged. He's overall stronger version of Mewtwo (but IMO not as fun to play as).
It's a great game but I prefer melee (Brawl is a great party game though and can be competitive). Lack of hitstun is deffinetly not a good thing. With hitstun you can combo in brawl it's probably only possible with MK. WD allowed characters who weren't as great like Mretwo (don't know what good it did him
), Samus (she's still good with out it but with it...2 good
) and IC.
IMO it requires far less thought. In melee you needed to think of what move you were about to do and how that was going to lead to a combo in brawl you can jump and try to land a dair hoping it will hit (and if it does hit then, because of lack of hitstun, you have nothing else to do then through a move before your enemy.