I can't help but suggest the title "Have you ever played Marvel?", since that is the comparison I most often hear.
Well, I'm coming back to P:M for good. Can't stand Smash 4's game play. Have any advanced techs for Luc been uncovered while I was away?
Well, I realized yesterday that Lucario is one of the few characters in the game that can utilize the knockback stacking mechanic effectively via Aura Bomb and fsmash. Though... the only time I see this being usable is if you shield break someone, and good luck doing that. I can't think of much else useful being taken note of.
I seriously need help with a matchups. Roy is a nightmare for me, especially when they play hyper aggressive.
In my experience (as we've got a few here in Texas), Roy requires a bit of patience due to his reach and how easily he seems to combo Lucario. Things worth noting in that matchup: tilting your shield is super important because of how early his nair and dtilt will shield poke, and how easy it is to perform high-low mixups on shield with those moves. Tilting your shield up primarily should cover for most other situations (like fsmash!). Most of his aerials, minus uair, can be shield grabbed if he lands close enough, to my knowledge, his utilt is easy to CC and punish, and his smashes and grab are super easy to punish.
Also fox and falco get to me pretty bad. Anybody have advice for these matchups?
Fox and Falco? Like the spacies? That make Lucario cry big blue baby tears?
You will get only a few chances per stock to deal damage, from what I've found. Make sure they are significant. Lucario's OoS options versus a spacie are often limited to grab, dair, or roll, and even that might not work. They're easy enough to combo once you get them in the air, but due to their fall speed, I personally have a hard time getting them high enough to get a comfortable combo going. Push them off stage and try for early gimps? This is the match that truly defines how limited Lucario is in neutral. If you figure out something, please share. XD