Probably every MU is a tough MU for Wario... Never shield is pretty much everyone's game plan to deal with Lucario.
Anyone with a really good OOS options can safely destroy Lucario's "shield" game.
- Bowser's fortress
- Sonic's upb
- Wario's upb
- Fox/Falco/Wolf shield out of shine
- Peach's upb, etc.
Also, all of Lucario's tilts can be CC'd. So at low-mid range percents, you can CC spam a high priority or fast move like shine and stop Lucario's chain. His dash attack, however, has some weird ability where it has a different effect on CC'ing.
The key to beating Lucario is simply baiting his dash attack. So far from what I've seen, it's every Lucario's favorite start-up combo move and it has a LOT of wind down. If you dash dance or even sidestep it, there is a lot of wind-up time for it to be punished.
Another key to beating Lucario is forcing him to approach you because his approach game isn't very strong. He has to ninja his way in and attempt to find an opening, but it's not very strong. Lucario is an opportunist.
Lucario also has no way of getting out of shield pressure. Fastest move out of shield is d-air which is more of a punish rather then reversal. I.e. Pillaring him with Falco is very strong.
Lastly, gimp the hell out of this guy. Extremely telegraphed recovery. If he has a super stocked, just assume he's gonna cancel his up+b into an air dodge and punish. But against a good edgegaurded, Lucario should NOT be recovering back onto the stage without being punished hard.
I can go on and on about Lucario. I've been using him solely since I've been playing and it's easy to see where his strengths and weaknesses lay. I, personally, think he is a spacies type character where his metagame will evolve at a rate similar to how Fox/Falco's did in Melee. He will become really, really strong later in his metagame as more people become skilled with him, but a lot of people will develop anti-Lucario games that will obliterate below-average Lucario players.
A frame 7 jab when so many other chars have a frame 2 or 3 jab? Lolz, a grab is usually 6-7 frames. That means you can grab DDD's jab if done at the same time. That's horrible, because jabs are oftentimes used to interrupt grab mix-ups.
Example: Falcon ditto. One Falcon attempts to jab > grab the other, but in between the two attacks, the second Falcon jabs the first one back to foil the grab attempt.
DDD can't even do this basic thing. Having to depend on.......Jet Hammer as a faster option than jab is just sad, considering how much lag that thing has.
Edit: Looking at the whole roster, I think (don't quote me on this) that DDD has the slowest jab in P:M right now. If not, then it's definitely one of them. Maybe Marth's is slower. Idk...
...Then don't use DDD's jab. LOL. You said something about DDD being a "grappler", but just because he has the best grab range does not mean he has the best tools to utilize them. Try exploiting DDD's strong air game first. DDD should not be grounded unless he's tech chasing or poking from a distance with f-tilt.