
I like your idea of him being the 2nd in their school- I even forget about that!
But technically, if he was 2nd, that would mean that he's power is higher than 6.3(Arlo) but lower than 8(Sera). That would make him around a 7 which would technically make him a god tier as that starts at 6+.
http://www.mangago.zone/read-manga/unordinary/nmt/manga/unordinary/c048/pg-16/
Also, your input about his power is what I too said a while back - they do say great minds think alike! ٩(๑❛ᴗ❛๑)۶

Except that, again... how does this explain almost the very first sentence in the webtoon where John states he does not have one, in reference to abilities? I mean, I love the idea of John having a power, because this actually makes it less cliched when he acts like a 'cripple'. He has to figure out how to suppress his powers while defending other 'cripples' or low-tiers. It's just that the fact that no theory ever seems to take that into account kinda makes it easier to dismiss those same theories. However, I must say that you may have, albeit inadvertently, hit on the reason as to how that came about in your own theory. Specifically, when you said that John's ability is mostly passive. What if he THOUGHT he had no ability precisely because it IS passive and it took Claire (Elaine? I get those two confused) to 'awaken' it, because she knew about it through one of her 'visions'? And take in to account what it means to be a 'cripple', although, mind you, I'm not saying that the author definitely chose the term precisely for that reason. A cripple is someone who has all the same capabilities that everyone else in the general population has but for some reason is prevented from using those capabilities. But I also would like to note that, if John is listed as the second most powerful in the school, why DOESN'T the rest of the student body know about it? Also, if the teachers at the school alone know about his status, maybe like the student body doesn't know about his abilities, at all, the teachers at this school don't know about the full EXTENT of John's abilities?

Maybe John can manipulate and is immune to other people's powers as long as he is more powerful than them? That's why Sera's power worked on him?

I think arlo is on the right track when thinking that john is trying to convince himself that he does not have powers so he does not rely on them

I think arlo is right when he made the comment about how john seemed to be trying to convince himself that he does not have an ability. So that he does not rely on his ability. I also think only a few people in the school know about john because that is what was done so that john could go to school. One person that seems to know for sure about john is the school doctor. I think this because of how the doctor warned john when he first started having troubles after sera left.

I think Arlo is right when he made the comment about how john seemed to be trying to convince himself that he does not have an ability. So that he does not rely on his ability. I also think only a few people in the school know about john because that is what was done so that john could go to school. One person that seems to know for sure about john is the school doctor. I think this because of how the doctor warned john when he first started having troubles after Sera left.

Then why didn't he go ballistic on the people who bullied him BEFORE he met up with Claire? I mean, we've seen him almost go ballistic on those asshole bullies who ganged up on him in the more recent chapters, the ones that Arlo saved him from but he didn't because he had PAST EXPERIENCE stopping him. What was stopping him in regards to the bullies we see him first encounter? The whole reason he seems to have convinced himself, too, looks to have more to do with his encounter with Claire and what happened AFTERWARDS than what happened with the bullies at his previous school.
So I noticed how none of the teacher's abilities seem to work on John. In chapter 1, one teacher has a stare that literally punches people in the face, but it doesn't effect John.
http://www.mangago.zone/read-manga/unordinary/nmt/c001/8/
http://www.mangago.zone/read-manga/unordinary/nmt/c001/10/
http://www.mangago.zone/read-manga/unordinary/nmt/c001/11/
Then, the infirmary doctor has the power to intimidate people, which also doesn't seem to phase him.
http://www.mangago.zone/read-manga/unordinary/nmt/manga/unordinary/c033/pg-43/
http://www.mangago.zone/read-manga/unordinary/nmt/manga/unordinary/c033/pg-45/
He could also sense whoever was following after Sera and him after they received the teddy bear at the mall.
http://www.mangago.zone/read-manga/unordinary/nmt/manga/unordinary/c011/pg-26/
But he was effected by Sera's ability. (But it's unclear if she has the ability to freeze time or if she the ability to move super fast. If she has the ability to move at super fast speeds, it doesn't necessarily mean her ability effects John...)
http://www.mangago.zone/read-manga/unordinary/nmt/manga/unordinary/c011/pg-42/
Also, also. There is a tier list for the Top 10 at Welston Private High School.
http://www.mangago.zone/read-manga/unordinary/nmt/manga/unordinary/c036/pg-63/
The first is Sera, and the third is Arlo. The second most powerful person is ???, and I'm guessing that is John. At first, I thought it was just someone we hadn't yet encountered in the comic, but thinking about it again, Arlo doesn't consider anyone at the school more powerful than him except Sera. So it goes to figure that Arlo doesn't know that there is someone in the school more powerful than him besides Sera. Hence, John's place on the list.
So, it might be likely that while John is pretty powerful, he's not god tier, or at least, not as powerful as Sera...
Also, also, also. Other people have said similar things, but I'll add my two cents. The fact that they put John in metal handcuffs after he was in trouble at this old school, and the fact that his record says, "Do not activate ability when handling situations with John," I'd vote that his ability is passive and somehow manipulates the abilities of the people around him. That means if people don't use their ability around him, or if they place him in handcuffs, he more or less powerless.
http://www.mangago.zone/read-manga/unordinary/nmt/manga/unordinary/c050/pg-6/
http://www.mangago.zone/read-manga/unordinary/nmt/manga/unordinary/c047/pg-53/
(=・ω・=)