The term overrated is thrown around too much these days, i mean take Staraptor, he is see no more or less than Pidgeotto, Noctowl and Tailow, because remember Ash HAS to have the regions main Flying type otherwise it would be impossible for them to find the random Pokémon of the day thats gone missing/ been kidnapped by TRio, as for Lucario i guess he could be classed as overrated, but he has a very big fan base and TV is all about ratings, plus you would have been kidding yourself if you didn't think he would be in the 3rd Gym episodes and the Iron Island episodes, and finally Pikachu, i feel it's unfair to class Pikachu as overrated, Nintendo practically rested the weight of the entire Pokémon franchise on him when it first started and even though it's slowly been taken off of him, he'll still be forced to carry a large chunk of it for the rest of his days, and be unfairly labeled overrated because Nintendo didn't think that (at the time) such a unique series could hold itself without a mascot (which to be honest i think it could).