Lucario, because it can learn psychic which has the advantage over toxicroak. =]
That's not even a comparison.toxicroak or lucario
Lucario has less resistances, but it's base stats are better:
Lucario:
70/110/70/115/70/90
Toxicroak:
83/106/65/86/65/81
As you can see, Lucario is obviously the better choice. It gets close combat, extreme speed, aura sphere, swords dance, etc. while Toxicroak gets suckerpunch, poison jab, etc. Lucario can also be a huge mix sweeping threat.
I didn't necessarily mean Toxicroak resists everything, but I meant it can help quite a bit on switch-ins. It resists most physical attacks (Bug, Fighting, Dark and Rock).What exactly is Toxicroak going to be resisting? It's too fragile to be taking many hits, so the Typing isn't a huge help.