Hi. I'm currently messing with the idea of writing a novel. I do have a bit of experience on RRL, but in that novel there wasn't a proper rival. Enemies who the mc sought to surpass and defeat, but not friendly rivalry. Would love any interesting ideas. Most novels I've read here don't have rivals as JP, CN, and KR author chose to write main characters who are unrivaled at the same level and grow too fast to have a rival/peers of the same level, so I lack any good reference material. Currently the rival I have most thought out is also a potential love interest. She appears just as the mc is achieving some success and is full of confidence. She is younger than the mc and from one of the most powerful family in the world. Cultivation wise she is one rank higher than the mc and in their first encounter she one hit ko'ed him. It was totally one sided, but she later says she had to take him out immediately if she didn't want to get into a death match. From her perspective mc was a threat, but from his he thinks he's weak in comparison to her. And in this arc they meet the mc is recovering from having his pride and confidence shattered, and is about building himself up and doing his best. Later on the mc gets to see her use her full power. Not only is she herself powerful, her family and personal connections, have allowed her to own powerful equipment and skills that maximised her potential and fight an opponent two ranks above herself. So he watches her win a fight that flattened the entire area in their wake, almost losing confidence again but has grown enough to not despair. This fight for the mc was to see the cold hard truth of how powerful the most talented and fortunate warriors in the world are, and what is required to aspire to reach the top as a normal person. Mc is talented in some ways, but not BS talented like this girl who is like top 5 talented wise in a world with a population of over 10 Trillion. The arc ends off with the mc promising to defeat her in so and so years. Oh and the funny romance part of this is that mc thinks that their fated fight is a death match to prove himself as strong, but she thinks its him wanting her respect and approval as a man worthy for her and to not embarrass him will also do her best even if it means killing him. She has ideas of romance, but when it comes to fights she is simple, selfish, and more so ruthless.
I think a good rivalry should have either a common goal that can only be achieved by one person, or perhaps the goal/path of one block the other, hence the conflict. It would be better if the conflict keeps continuing for the entire story, except the stakes and goals evolve over time. The rivals should have different personas and characteristics, but at the same time, something common, allowing them to have an understanding of each other. To me, the gold standard for rivalry in storytelling is set by Naruto and Sasuke. They start with both trying to become the best ninja and hokage, and then in the middle become practically enemies, since their goals are in conflict. But at the same time they have a certain understanding of each other and respect. It was basically one step short of a gay couple.
Vegeta in dragon ball z legend of the super saiyan Super Nintendo game. The hidden boss at the end after the final boss. basically what sasuke did in the series about boruto’s dad
A good rival shouldn't just be a measuring stick for the protagonist's power. In order to help develop the protagonist's journey, the rival should also challenge the MC's beliefs, ideals, etc., either through opposition or by providing viable alternative paths. This creates a dynamic through which the rival can interact with the protagonist through more than just a contest of strength. In fact, a difference in beliefs will probably help color their interactions even more since the story can then test the convictions each side has.
There a re various ways to go about it, but for rival a conection needs to be stablished, at the same time each character needs to be independent from the other, no self-dependent. One migth be the goal of the other, and the superior one knowing the upstart is coming makes him improve himself or somethign like that. Or you can have both coming from the same place and trying to up each other. Now your idea is original and depending of the context it can be great. As with any good story watch out for the details, there is the core of any good story.
The way I'd probably do it is to treat another character with the same love I have for the MC, but make them clash with the MC on their path to a common goal. Also, more screen time and scenes together. For inspo - look at any decently popular sports anime/manga (and consider the tons of BL doujinshi about the MC + rival character) to see how the dynamic goes. Slam Dunk is great. Shamo as well. Vagabond in later volumes. Kuroko no Basket, I guess. Haikyuu.
That's the modern way. Personally I do have a bit of a weak spot for the totally vile villain, that scehemes and betrays and cackles with maniacal laughter when given the opportunity (See old Disney villains, some DC villains, most JRPGs villains) This type of villain needs only be entertaining
I always found the best rivals are the one you can't help but feel a mix of admiration, approval and jealousy towards. Especially when they have the same background. Because the more similar you are, the more compared you are. If your making a realistic, non goody too shoes that feel raw emotions including the bad ones, you don't want the protagonist to have the ability to look at the rival and go, 'its only cause they have more opportunities than me, they are there.' But if you take that avenue of such rationalisation away, the mc can't help but acknowledge they need to step in up. And if their backgrounds are different, you need to make their potential or their existing power on the same level. Just so that the common ground is maintained to bounce off the different ideologies, lifestyle or expectations.
You can always copy what pokemon red and blue did. The rival is always one step ahead and seems to have an edge over the the protagonist.
you have many choices you can create the usual bully that uses his own family and authority to bother others or you can create the "student council president template" as in the perfect guy who is the top but missed up in the head, or maybe a childhood friend who left him behind after he saw his low ability (x1999/code geass)
If they're romantic, typically you want to be good to each other. Always being on each others arse must be exhausting. Give them a life outside of it. It's like how muscleheads can still be a straight A student. Rivalry is a healthy relationship with tension, it's a tether that causes both sides to feel urgency and a sense of awe.