Genius as in no bullshit power-leveling by super rare treasure/ability or reincarnation trope of some kind. Just working hard and spending time on their power without the use of super pills.
That would mean 100% of the wuxia novels almost? Wait now that you mention it.... just what is the standard for genius in this thread?
Immortal Mortal. Mc is mortal. Tries hard to be a cultivator but has shit talent. So he has to rely on drugs...
Most MCs are not what I would consider actual geniuses. They rely heavily on bullshit lucky encounters, experienced/powerful teachers, and consumables that increase their strength for them. And I'd say pretty much every xianxia has at least two of those three things, and most will have all of them. Even the handful of geniuses (like the MC of Stellar Transformations who took a mediocre cultivation method and improved it massively by the end of the story) only made it to the ending because of bullshit luck piled onto bullshit luck. Talent? You don't need talent when you win the lottery, find the best teacher in the world, and keep stumbling on side-effect-free enhancement drugs.
obviously he is a genius he's a mc.... the op didn't ask for a rube mc he asked for one that takes a long time to become powerful..
Hmm... Goblin Kingdom I guess ? He is far from a genius about what I know. Gu Daoist Master... of course, he is not. He is just too smart and is living his life once again, though he has trouble staying ahead of everyone. And also, A Sorcerer's Journey
They mentioned that it took him like 8 years for the realms before Life Destruction, but Life Destruction took an entire 10 years
Depending on how you define it, Immortal Executioner. It's a "Personal Reset" story, where the MC returns to his past. He got to an impressive level in his last life, but was still just cannon fodder. He gets a reset instead of dying, and uses the information he couldn't of possibly have had in his last life to improve himself as much as he possibly can. At the start of doing so, he is given knowledge far beyond that he had previously (even in his last life). He manages to be able to do this beyond what other's would typically be able to due to retaining some cognitive ability and willpower from his past life. In addition to that, growth in this series takes time, and growth benefits from taking that time. It's not unusual for things to take years. The MC, specifically, isn't even trying to "rush" his growth, and is instead trying to set as stable and as powerful a foundation as he possibly can. Negatives that go against this request... he does end up presenting himself as a "genius" in cultivation, pill refining and energy control, and has an insane memory.
The Crimson Dragon. the mc is, without a doubt, not a genius. Spoiler mostly everyone thinks hes stupid and he snaps back when a certain someone calls him a retard. good stuff!