I wasn't necessarily talking about simply jumping on the ledge to gimp him (although that can work sometimes). But once you get Lucario to the point where he has to use the maximum length of extreme speed to recover then its pretty easy. If Charizard can get an fair even at low percentages Lucario is in trouble. Likewise Squirtle can use his aerials to get him far enough away from an edge to grab it. Certainly Lucario isn't at a Link/Olimar/Ivysaur level of gimpability but its a weakness worth noting.True, but somewhat countered by the curve, the speed and (on some stages) the wall cling. This isn't Fox, mind: even if you edgehog, Lucario can easily land on stage 90% of the time, especially with proper DI. Of course, you can punish him for that, but Lucario is by no means easily gimped. You also have to take into account that he can quite safely defend himself from edgeguarding with any of his directional air attacks, as well as Aura Sphere (situational).
I'd recommend starting as Squirtle over Charizard due to Lucario's early chaingrab, but they're both viable. When starting as Squirtle, though, you might want to consider switching to Ivysaur early - if you don't kill him fast, he'll become SUPER LUCARIO. Not only will this allow you to avoid that to some extent, but after KO'ing Lucario as Ivysaur, you can deal some additional damage and lessen the impact of Lucario's chaingrab when Charizard comes in.
The order I'd recommend:
- Start as Squirtle.
- Switch to Ivysaur when Lucario and Squirtle both get medium-high percentages.
- Finish the stock as Ivysaur.
- Tank Charizard throughout the next stock, unless you manage to kill Lucario while Charizard is at a low %. In that case, switch to Squirtle when you get the kill.
- Again, switch to Ivysaur once Lucario and Squirtle get to medium-high percentages.
- If necessary, switch to Charizard to finish the job.
This switching pattern will allow you to take advantage of the fact that at low %, Lucario is Baby Lucario.
Also I wouldn't try Ivy at high percentages for Lucario. Ivy racks up damage well but can have trouble landing his KO moves which is exactly what you want to avoid.
Btw do you know approximately at what percentages Lucario can chain Zard?