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.
Yeah but without this trope we wouldn't have Char Aznable and his cool sunglasses
Char gets a pass for being invented in the 70s or whatever
That beautifully awk Quattro/Amuro handshake
Eventually it falls apart.