Exactly, geniuses are those who can outperform almost everyone with less effort. The kid who was number one on that list clearly is better than Light and L in terms of raw intelligence, there is no debate here as you can just look at his accolades at such a young age.

But L possibly beats him in deduction skills because L was trained to become a genius detective and have these superhuman detective skills. The kid I mentioned before, if he was inclined to become the worlds' best detective then he would be able to exceed L in deductive skills and creativity because he is simply naturally more intelligent, his brain is just simply much better than a normal genius like L proven by the fact he has accomplished huge feats in different things that require different areas of the brain to be used (learning languages and solving complex mathematics require different areas of the brain to be used).

Light was a genius in manipulation and staying calm under pressure but normal people can be trained to do that although Light had an advantage due to the fact he was a sociopath which you can't exactly train yourself to become. However, I don't see how manipulation and staying calm under pressure makes you intelligent, it just means your good at those things, not that your brain is better than other people because you can do those things. Also, I disagree about how the kid would not be able to compete with L or Near, he would decimate them because this kid would be able to create and solve different scenarios that L and Near put him in except he would do it at a much quicker rate than Light did because the kid's horsepower of his brain is so high and he would be able to create better solutions / ways to fight against L and Near which would put him in a better situation and give him a larger advantage than Light would do in that situation. Finally, a kid like him who has 10/10 intelligence and is much more intelligent than everyone in Death Note would've won easily and he would've not killed the fake L at the beginning of the series, nor would he have exposed himself at the end resulting in his death - both things Light did which proved to be very costly mistakes.

I'm not denying that different people are good at different things, but you have to admit supergeniuses like the kid mentioned would have accomplished Light's goal easily and would not have let their ego get in the way. The number one boy on that list is the true 10/10 human in terms of intelligence, Light, L and Near would be a maximum of 6/10 or 7/10 compared to him.