Do you think a talented sidekick would not overshadow the protagonist? I plan to have a more talented sidekick (my plot demands it) is it possible? Are there any book where sidekick is better than protagonist?
Sure, I don't see why not. One example that comes to mind is Glen Cook's The Black Company. The POV character and protagonist is the company's annalist, and so he's the one that is writing everything down. And indeed he takes a central role in the action of the story, but there are other members of the company around him that are better fighters, or who can use sorcery, or who are in charge and give orders, etc. I don't know that I'd call them sidekicks, but the main character (Croaker, by nickname, who is also the company's physician) is not the most talented of them when it comes to things you might traditionally think of in an adventure story (fighting, etc.). Orson Scott Card retold his Ender's Game book entirely from the point of view of a secondary character, who is definitely less talented than Ender, and that seemed to work well for him. To use a more popular example, in LOTR I don't think there's much question that Frodo isn't the most talented member of the Fellowship. He isn't the strongest, he isn't the best fighter, he isn't the most knowledgeable, and so on. In that case, I think the fact that he's somewhat ordinary is part of the point.
Inspector Gadget (the cartoon, not the movie) was a great example of this - the MC was armed to the teeth with all manner of tools and weapons, but had no clue how to use them effectively. His niece and pet dog worked out the criminal plot in each episode and guided the Inspector to victory, often without his knowledge.
