>>23189346It's more than that. There are Mary Sues like Garchomp and Salamence and in Gen 3 Metagross and Tyranitar were unstoppable. Genies are OP now, too, but not the way Lucario is.
All those other mary sue mons have their stats, they have their strong suit and their still-strong-but-weaker suits. Lucario tries to make literally every suit it has be its strong suit. And as
>>23189376 mentioned, even outside of the gameplay with that lore and that voting tournament and just everything about it screams that Lucario just has to be the best.
And not best in a cool way. Best like, "Oh, I'm going to buy a new car, then people'll like me." Or "I'll treat everyone to dinner. Then they'll like me." Or "If I make my house the coolest place to hang with video games, huge tv, and food, then they'll like me."
If Lucario had just been a steel/fighting that was good physical and could pull off a surprise special every now and then, his typing and design would've made him liked all-around.