Gimping him is very easy as his recovery has no hitbox.
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.