As far as allied gods Zhong Kui works well with, I honestly haven't found him to work particularly well with some gods more than others to his bennefit. Of course there are the standard picks like Aphrodite and Khepri, but those are more universally helpful gods and don't necessarily benefit Zhong more than anyone else.
There are, however, certain team compositions and gods who like having a Zhong Kui on their team. Picking Zhong for the mid lane means the solo lane has more leeway in the gods they can pick and don't necessarily have to pick up a warrior if that's not what the situation in that lane requires since Zhong is so tanky and can be a front liner instead of the solo laner. If they do pick a warrior, then your team now has three front liners with you, the solo laner and the support. This is really beneficial for late-game hyper carries like Kali, Artemis and He Bo who will have the team doing everything they can to kill them quickly. With an extra front liner, it becomes much easier for these hyper-carries to stay alive and do their job, which is to do insane amounts of damage to carry your team to victory.
Note that these enemy matchups mostly come from my personal experiences and are therefore subject to just that, so be sure to leave a comment if you take issue with the reasoning behind any of these matchups.
Good Against
Belch of the Gods is a really important ability in
Bacchus' kit, and being able to easily cancel it out with your
Book of Demons to cancel his stun for both you and your teammates will make him much less effective against you.
After he jumps in to initiate, it's easy to just use your
Book of Demons to peel him off of you after which he has no way to hurt you. If he ults you, then activating your
Recall Demons and/or sprint can usually ensure your saftey.
Allot of
Cabrakan's effectiveness comes from his ability to lock down gods with
Tremors. Similarly as with Bacchus, you are able to use
Book of Demons to completely cancel this ability out. And since
Tremors is usually the last ability in his attack chain, you are free to walk away from
Cabrakan with no danger of him being able to chase you, essentially making him useless agains
Zhong Kui.
Zhong Kui matches well against just about any other mage, and
Chronos is no exception. While
Stop Time can certainly mess your day up, aside from that
Zhong Kui can do just about anything
Chronos can do with the build in this guide and more, which should make engagements between these two very one sided.
He Bo is a mage who counts heavily on his burst damage to bring the enemy mid laner from 100%-0% very quickly. The problem he has against
Zhong Kui is that Zhong has enough health and protections built up so that by the time
He Bo's damage starts to come online, you will be able to fight and bully or kill him even after he has used his combo on you.
With predictable and punishable wave clear and no real escape,
Eset is an ideal target for
Zhong Kui's bullying playstyle. Her ult is really good at countering yours, but other than that it's just about as ideal of a matchup as you could hope for.
A mage who has trouble bursting down
Zhong Kui once you've built up enough health, you should be able to do much more to him than he can do to you. Plus
Janus' escape ability relies on him not having any active crowd control effect on him, so your five second slow from
Expose Evil is able to lock down and shut down this slippery god.
Kali is a late game beast who struggles from a weak early game. Usually her sure fire way to get out of her early game rut is by picking up some kills from squishy mid laners with no escape.
Zhong Kui is anything but squishy, and
Book of Demons can safely peel her away for you to escape her. Similarly to
Bakasura, if
Kali uses her ultimate on you then your ult and/or sprint can usually save you. Just don't let her get to late game, where players will usually build
Hastened Fatalis and
Qin's Sais and really begin to screw you up.
He'll be a huge annoyance early game, but once it gets to late game he'll be damn near useless against you thanks to your large health pool, solid protections and easy to confirm peel for melee gods like
Loki.
Another god who relies on bursting his enemies down,
Poseidon will also have trouble doing this against zhong qui, again because of his tankiness. He's likely to outclear you early game with basic attacks to match yours in strength, but once your waveclear and
Telkhines Ring come online you should start to be able to bully him just like the rest of the mages. His ultimate will be the only thing you should be worried about from him at this point.
A
Ra who really knows what their doing will be able to hold their own against you, clearing the wave with
Celestial Beam and healing in the back of their tower and out of range of your poke to hold their lane against you, but seeing as how I've yet to play against anyone who has done this, I'll put
Ra in this "good against" list. Most players will mistakenly try to poke you with
Celestial Beam and let your minions into tower where you can easily poke him. Either way,
Ra is a mage and
Zhong Kui is the mage slayer.
If you position yourself just right during a fight with a
Ravana, then he should have a very tough time fighting you, since all of your abilities have just a little bit longer range than his and your sustain is a bit more potent. Should he ever manage to get close enough to you to start dealing his damage, just peel him off with
Book of Demons and walk away.
Scylla is indeed a very scary monster in the late game, but if you need a god who can shut her down early before she gets to that point, then
Zhong Kui can often be a good pick. You'll be able to outclear her in the early game and your poke damage will really mess her up. If you can manage to bait out her escape ability, then she can easily be killed if you commit to it.
Your heal can really screw up his execution ultimate, and without any hard initiate or way to chase you down
Thanatos will have a hard time trying to gank and kill you.
Thor's
Berserker Barrage can easily be canceled with your stun, negating a huge portion of the damage he would be able to deal to you.
If you can manage to get past his abilities he would use to zone you off, then
Zeus is a very easy kill. Your effectiveness against him will really begin to shine lategame, where your tankiness will allow you to walk all over him.
Bad Against
Hunters in general Zhong Kui can have a tough time against in some scenarios, but
Anhur is probably the one he does worst against. You can easily be pinned down with
Impale and
Shifting Sands, and his built in penetration can allow him to really screw you up.
Without any hard escape,
Zhong Kui is very susceptible to
Bastet's cat call ultimate. Your
Book of Demons will only delay the inevitable against her cats early game, but you will begin to do much better late game where the cats will actually be more of a help since they can be easily killed then and you can heal up off of them. Before that time, however, be very weary when fighting a
Bastet.
While you can use your
Book of Demons to completely cancel out her
Bludgeon, you will be left without your effective basic attacks if you do this, plus
Bellona is able to disarm you, completely stopping you from using your basic attacks altogether. It's an ideal matchup for you if you find yourself in the solo lane, but you will be in the mid lane most of the time so you'll mostly be fighting
Bellona in the teamfight stage. If the player builds her in a certain way, then a good
Bellona will be able to completely stomp you.
Erlang is a very sticky god, able to pin down anyone without a hard escape and killing them without so much as a fight with a root, built in permanent fatalis, a dash-knockup and a huge taunt in his kit.
Book of Demons is not usually enough to peel
Erlang Shen away from you, making you easy pickings for this currently overpowered god. Some much needed nerfs will hopefully knock him off this list.
Guan Yu is very good early game against zhong kui where he can beat you at your own game, being aggressive to poke and healing up afterward. He can use his dash or his ultimate to re-initiate on you after you've used
Book of Demons to peel him away. Fighting
Guan Yu can be very frustrating until you build up health and passive stacks.
Possibly the most mobile of all hunters,
Jing Wei can easily stick to you and kill you if she is played right. Her
Explosive Bolts are especially potent against
Zhong Kui who has such a large hitbox, so I would recommend not picking a fight with
Jing Wei if you can unless you have some sort of advantage over her.
Mercury players will build allot of speed and usually crit chance as well, meaning they can chase you down even after you've stunned them and apply more sustain damage than you can do to them.
If you're a god who likes to move or use abilities, then
Nox is a counter to you. You can outclear her early game, but as soon as it gets to mid-late game, there will be literally nothing that you yourself can do to fight her without a large amount of team coordination.
With different abilities at her disposal to engage with,
Serqet is a difficult god to peel away from to be able to escape from her. Plus her ult completely negates healing, canceling out your sustain for a brief moment.
Zhong Kui would actually be a good counter pick against
Skadi since his basic attacks can hit her dog twice, essentially killing it twice as fast. The only problem is that while
Skadi is using her ultimate the dog is invincible and is just as fast as you even if you activate a sprint, meaning you can do literally nothing to save yourself outside of using a sanctuary to save yourself from 2 seconds of damage. It's like
Kali's
Destruction, times two, on steroids.
Susano excels at sticking to gods and keeping them in range of his basic attacks and damaging abilities. With a teleport, a dash, a pull and a knockup in his kit, your
Book of Demons won't do much to peel this pesky god away from you.
With twice as much of a kit to work with as you do and just as much sustain, pray you never have to go into the solo lane against a decent
Tyr player. Good luck trying to stun him while you're knocked up into the air by his
Fearless combo. (spoilers: you can't)
Vulcan is a direct counter against
Zhong Kui in the midlane.
Vulcan can safely zone you out not just from himself but from the minion wave as well. His entire kit is centered around keeping aggressive gods like
Zhong Kui away from himself, meaning you'll have a very tough time trying to play aggressively against
Vulcan. In this matchup, you're better off taking a more passive approach, not letting him poke you too much and just calling it a draw at the end of the laning phase unless you coordinate well with a good jungler.
Your purchase order sections could do with a little cleaning up as they're a bit messy and unclear at the moment (for example it looks like you're suggesting that you only purchase level 1 Shoes during your full build), particularly for your main build. Your main build looks decent, to me, though.
The info you have in your guide is great as well, but it is VERY wall of texty, which makes it a chore to read in a lot of sections. Some formatting and whatnot would help a great with breaking up the walls of text a bit.
I think you have a great foundation here, but you need to make some improvements to make the guide easier to look at.
If you'd like, feel free to look at my guides for some formatting ideas for your own guide (Raijin or Skadi are probably my best formatted, though they're outdated by a few patches).