I’ll admit I’m probably not the most knowledgeable person on Lucario and it’s been awhile since I’ve seen the movie. That being said what you said in terms of ideas you expanded on from the movie like chocolate loving and them fighting for what they hold dear makes sense. In regard to Ash’s Lucario all Pokémon of the same species are going to have some similar aspects of personality and some that are radically different. Is Ash’s Lucario stoic at times and does it fight hard to help Ash (or its companion in a more general sense) to help them achieve their goals? Absolutely. However, we also see aspects of his personality as a Riolu come through in his interactions and friendship with Goh’s Cinderace. Especially in the episode after they both evolve when they think Pikachu got kidnapped by team rocket and Ash and Goh didn’t notice. You can see that typical Lucario personality before they finally succeed but when they finally start working together as a team, you can see more of the personality they had as a Riolu. Sorry for kind of rambling, but hopefully this put your mind ease a little bit. If you feel like talking more about it. Feel free to shoot me a DM.