Umm. I didn't know Lucario had the same B move as Mewtwo Wonder what else they have in common.

Not much actually. Almost everything else is different.

EDIT2: I can't remember if it's been said before, but is L Cancelling, like, automatic now? The downtime after WW Links' Down+A seems very short.

L-cancelling was removed completely. It's only automatic on some attacks. Others still have long delay, such as Snake's back air. It depends on the move.

So I take it that L Canceling is an animation/ move/ recovery/ recoil cancel? If so... I'm glad I didn't play Smash Brothers that much.... because a change like that would have been a game breaker for me.

It stands for "lag cancel." Basically what you do is hit either L or R (or Z in SSB64) right as you land from an aerial attack. In SSB64, your lag was completely reduced, allowing you to attack instantly after landing. In Melee, that lag was only cut in half, but was still very useful for comboing and avoiding shield grabs after landing an aerial attack.

Just found a video showing gameplay between U.S. and Japan. There doesn't seem to be much lag at all.

http://www.youtube.com/watch?v=dxRAmlL8k78

L-Cancel was also vital in some characters' gameplan, and you basically HAD to use it to have any chance of winning against anyone who had an idea of what he's doing. Link's dair is a crazy good move for example, but it lags for HOURS if you don't l-cancel it and it gets himself killed if used anywhere that whiffs.

I'd recommend watching all these videos to learn a few advanced techniques before the tournament. Some don't apply anymore (wavelanding, wavedashing, l-cancellingm shffling) but others (dashdancing, out-of-shields, teching, edge hogging/edge hopping and such) are still very useful techniques that are very good and easy to learn. I'd recommend watching match videos too but it's pretty useless now seeing as how everyone sucks more or less and nothing gamebreaking has been discovered just yet.

http://uk.youtube.com/watch?v=QlSxR3ebOzc
All of the character taunts

http://uk.youtube.com/watch?v=3qrCRrxbEnE&feature=related
And a secret Lylat taunt. Can't understand anything, but it's there.