The rival.
Especially the douchebag Machiavellian type rivals that the main character ends up friends or teaming up with after the main character 'proves their worth' to them by being stronger. No character growth outside of now they work with the protagonist.
I really want this trope to be subverted one day, like the douchey rival shows up and everyone is just like "Wow what a dickhead" and just relentlessly bullies him until he goes away.
The rival in Hikaru no Go is definitely not portrayed as being evil. In fact the entire reason that he becomes the rival is that Hikaru makes a careless remark about being a Go champion (because at this point he's never worked hard to win), and the other character rightfully admonishes him for underestimating how much work it takes to be a top level pro. In the end, Hikaru's character arc is completed when he falls in love with the game and wants to work hard to become good at it himself, and Sai's character arc is accepting that it's finally time to move on and let his student play, rather than selfishly wanting to keep playing himself.
Come to think of it, the only people in HNG who get portrayed as evil are the cheaters and the assholes, but even then the story makes it clear that they had to work hard to get a ton of game knowledge to be competitive.