Just to add on, Corneria is horrible because it has an extremely low vertical kill zone, which is bad for lucario's sub par vertical KO resistance, and having the back area which can make early kills is not very safe for Lucario's "aura boost" factor either.
Norfair has lava, limited spacing, and while it is easier for lucario to recover, its also easier for other characters (like heavys who need to be gimped).
Lylat screws with everyone in terms of recovery, but lucario (and space animals) are some of the ones who have a tricky time with the stage (when it tilts, it's been found that the ledge/side being tilted turns less into a regular stage and more into "wall" physics, hence why the Reversed Reverse DT glitch was possible.)
Rainbow Cruise has easy kill zones (once again bad for aura boost), and with the platform heavy stage that it is, it makes scary aerial characters (like MK) kill us easily, and should only really be used against weaker aerial games (like Diddy's).
Nick, don't put on "airs". We need to recognize that player skill is not again the only factor needed to determine. If you are so incensed to show "how great and powerful both you and your opponents are", may I suggest you at least have videos at the ready to prove it? I really don't want this thread to get locked, and with what seems to be going on, Unless you contribute to meta-game discussion instead of generalized "flaming/angsty" posting, I will have no choice but to report (which I have not ever wanted to do, but I will). SWF is here for people who can handle it, and it seems that you insist on telling us that you can't. Don't want to sound mean and somber, but like I said, if you can't handle discussing actually useful things (seriously, who's side are you on, flaming half the lucarios here who actually do know that lucario has weaknesses?), I'm going to have to remove what could close my thread down.