Mario relys on mostly gimps. Grabing the ledge agaisnt lucario puts you in a very bad position, and lucario doesnt grab the ledge. He recovers high and punishes any advances with a dair. What you do normally doesn't work on lucario. He makes things complex.
Do you really play lucario?
I'm sorry, I was just saying, you know, how IN THAT SITUATION Lucario is so ****ing low and recovering at such a ****ty angle that Mario could've grabbed the ledge and waited out Lucario IN THAT SITUATION where he's so low, and if need be maybe hit him out of his UpB (probably with BAir), for at the very least free damage and putting Lucario back in a bad situation, and at best outright killing him depending on percent/stage boundary, instead of using Cape. Even if he DIs that, he's still in a crappy position and might be forced to use his second jump, again dependent on percent/boundaries/DI/If I can wallcling on that particular stage.
He punishes low approaches with a Dair, yes. But unless you keep running at him at the same angle under him going for the same stupid **** over and over again there's no reason for you to ever get hit by it more than a few times. You have predict he's going to DAir, because he's predicting you're going to attack him from a punishable angle. This is an aspect of EVERY FIGHTING GAME EVER, the idea of countering your opponent's counter to your action. It's the basis of mindgames and yomi, or reading your opponents mind.
For example, say I recover high on Battlefield, as I should with Lucario, and I see you on a platform below me while I'm doing so. I would venture a guess that you'd probably want to hit me somehow. I see you're mostly below me, so I decide to DAir. You, knowing the MU and the basics of a Lucario player's playstyle, would probably be able to guess I'm going to DAir, so you decide to jump to my side instead of directly below me, avoiding the DAir hitbox and counterattacking with your move of choice, probably NAir or BAir. Now let's say that same situation happens again, but I know you know I'd try a BAir. However, I also understand you could also approach me from below if I try to FAir/NAir/whatever to catch you at my side. Also, the option to simply wait me out if I airdodge is also in my head, as well as you even waiting for me to DAir near the ground and counterattacking THAT with something (pivot grab/Dash-in USmash/spotdodge into stuff/stutter-step FSmash/etc.). With all of these variable counters in my head, I have to be careful not to pick the wrong choice in this situation so as to not get punished.
There are tons of situations like this that pop up all the time, that people take for granted because of really good options that have limited weakness. HOWEVER, it is YOUR JOB as the player is to find the weaknesses and exploit them. If the Lucario player always recovers the same way, find a way to punish it. If he frequently DAirs, STOP RUNNING INTO IT and think of ways to get around it.
But of course I know you're going to say "well you can't always predict your opponent," and I'm going to say, "of course, if he isn't ****ing ********." How about the "my character relies on gimping for kills" statement, where I say "well if I know your character is reliant on gimping, I'm gonna do my ****edest to avoid getting in a situation where I could get gimped." If your character's kill potential is so one dimensional that you have no realistic options but to gimp, then that's his and your problem, not mine or Lucario's. If anything you should whine about buffs for onstage killing.
Goddammit another wall of text >_>
I wish we could stop arguing about this once and for all