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.
Counterpoint: I will never get tired of watching the protagonist and their rival team up to defeat the greater villain
Goku and Frieza fighting together for just one episode of the last fight in Dragon Ball Super was :chefs-kiss:
Also, for the old heads out there, Anubis teaming up with Ryo in Samurai Troopers/Ronin Warriors was so good.
The anti-hero becoming a reluctant ally is my favorite trope.
I agree it was super wholesome when Goku teamed up with Space Hitler
I mean you have a superpowered derelict father/husband and ubermensch with a god complex teaming up with an arch-capitalist corporation to galavant across time and space to do a colonialism and steal artifacts, but did you know he talks like a farmer, hee-yuck.
:joker-troll:
Freiza does genocides purely for profit as a galactic landlord/ real estate guy.