Well Lucario is a beast if played in the right hands like Trela or Junebug. He has quick moves, combos, disjointed hitboxes, rolls that are on par with our own, and insane kill power when he has enough damage.
The matchup is kind of determined by who gets the first kill because whoever dies first is going to have a tough time coming back for a while.
Obviously our arrows are no joke in this matchup. Lucario is floaty and if we get him offstage we can get at least an extra 10-20% from just arrows if we aim right. That added to grabbing the ledge is a guarenteed free hit because Lucario's extreme speed doesn't have a hitbox for whatever reason and can't knock us off the ledge so he is forced to land onstage with his up b.
Aura sphere is a big part of his game as well, but we have mirror shield and a charged aura sphere with double the knockback will kill lucario at 100 so don't forget to down b. Make him more afraid of his own move. Although, when we are offstage and Lucario tries to aura sphere us, don't think that mirror shield will protect you 100% of the time because if we land on top of the aura sphere it won't be reflected because it touches our feet. I've died offstage from junebug AND trela this way I believe.
He is floaty and light so fresh fsmash at about 130 should do the trick. This is crucial because if you land a kill move and don't kill him then he will give you hell for it. You might lose 2 stocks before he loses his first.
CP'S: Final Destination is good, but everyone bans this against us. Go here if they don't ban it though. Safest place for Pit. Other stages are Halberd, Rainbow Cruise (Don't go here if they have pocket metaknight), and maybe Delinfo because the transformations where the blast zones are small might hurt us.
BANS: Frigate because He can wall cling on the part where you can't grab the edge and we can't. June likes to go here so it must be good for lucario in other ways. Yoshi's, Picto, and the pokemon stadiums are also bad stages to go to. One we can't fly over them, and two Lucario will wall us here forever. He can just spam forward smash and keep us on the ledge. We also can't plank as well on these stages.
Bread and Butter Moves: Jab combo is always nice, retreat dair his aerial approaches, Usmash is a great punisher in the mu, arrows offstage, and spaced uair.
Things to watch out for: His dair stops momentum so he may use it to stall in the air or he could use it right over the top of our heads. If he is right above us then expect him to use it, don't try to punish before he uses it either because it comes out lightning fast. Shield it then usmash oos. It also defeats our uair if it hits us in the middle of it so that's why we have to space it. If he is comboing you always expect him to end it with aura sphere so if you think the combo is over it isn't just yet. His uair and bair offstage are like secret kill moves with lasting hitboxes so be afraid of those. His fsmash has IASA frames so don't try to punish the ending lag. Instead predict it and punish the crappy start up with dash attack. They usually cancel their second jab into a grab, SDI away and we might be able to escape.
How to approach it: Uhhh, don't approach? lol If you need to ease your way in there by walking not running so you can shield whatever punish he tries. If you have momentum then rush in there, but do it smartly by getting reads and using safe yet rewarding moves depending on the situation.
things to keep in mind: fthrow>ss fsmash works I believe, since he has like no fall speed moves that kill of the top like glair, dair, and fresh usmash can be useful kill moves around 140 to 150, DO NOT USE ANGEL RING CLOSE TO HIM because he will punish with an easy fsmash. Be very careful when trying to get back from the ledge because chances are they are hungry to fsmash you.
50:50 until the first stock, then 55:45 in the person who's winning's favor.