What makes oni a good killer? What are his strengths and weaknesses? What perk builds should I use?

He is a great snowballer with a weak early game. If people dont know how to counter him, he can down multiple survivors in one go with infectious fright. You can still loop him though, especially in jungle gyms, not for long but enough to waste enough of his power. Perkwise, Corrupt for his weak early game, infectious fright to slug and the rest is up to you. I like Enduring and Sloppy/Pop last.

Oni I would say is my quaternary or quinary pick for killer, interchangeable with Hillbilly but I typically lean toward Hillbilly more than I do Oni just because Hillbilly is more consistent and has access to his power all the time. For those starting out he's (Hillbilly) far more noob friendly and if you're looking to get a feel for Oni or practice before you get him you should really be working on playing Hillbilly. There's a lot of skill transfer that goes on between the two

Biggest weakness - without his power he's an m1 killer. This can be absolutely, intensely, excruciatingly, DEBILITATING especially if you're going up against a good team of survivors, since you won't have your power at the start of a match until you start getting licks in. Problem is, it can be difficult to get licks in if you don't have a power so you can see how a bit of a paradox forms there when playing the Oni.

If you're going up against someone who is really good at running loops to the point where you can't even hit them once, it's gonna hurt, and you can be in some deep trouble since hitting fresh, healthy, uninjured survivors is precisely how you get your power. So you should be aware of that, but once you do have your power you can quickly snowball pressure across the map and on loops that you previously couldn't before forcing survivors to drop pallets early or restrict how many times they can use a loop.

You should also be careful with actually aiming the power, it can be notoriously difficult to actually hit a demon strike if you're not practiced and survivors will really try to take advantage of that first person camera. Be aware, predict, practice, and you should be good.

The perks that I like to run on Oni are all anti-heal perks, you want to keep survivors injured as much as possible to keep them bleeding leaving blood orbs everywhere they go which you can pick up to get your power but also can be a somewhat decent tracking tool. And of course keeping everyone injured also makes it easier on you when you need to go through chases without your power as well. So anything that has to deal with healing or survivors in the injured state synergizes perfectly well with the Oni so we're talking: Nurse's Calling, Sloppy Butcher, Thanataphobia, Coulrophobia, Stridor, Bloodhound, Blood Echo, etc. and two of Pyramid Head's upcoming perks which are not yet in the game Deathbound and Forced Penance also fit into this category so look out for them.

Basically anything that works for the Hillbilly works for Oni. The Hillbilly uses a lot of perks that provide intel of where survivors are so he doesn't have to waste time searching, and can use his incredible speed to apply pressure on the right place at the right time almost immediately. In the same way the Oni can do the exact same thing, so perks like BBQ & Chili, Discordance, Surveillance, Gearhead, Thrilling Tremors, etc. are also good to run

There are a bunch of other individual perks that work well with The Oni for their own unique reasons that don't fall into a specific category of perks, like Infectious Fright which can help you snowball a lot of pressure bouncing from one survivor to the next. I saw someone else say Monitor & Abuse which I never thought to run on Oni but it sounds like it's worth a shot and falls into that category of "unique perks with unique effects that affect a killer, uniquely". Another one of these perks I would like to mention is actually Pyramid Head's last perk, Trail of Torment, you kick a generator and become completely undetectable for 15 seconds. Now imagine you activate Yamoaka's Wrath bellowing your thunderous war cry, a violent roar that's heard across the map, you kick a generator, and immediately begin gunning it to wherever you know you need to go. Similarly to the logic behind running monitor & abuse on Oni you're silent (aside from you're heavy loud-ass footsteps) as you dead sprint across the map with no terror radius allowing you to more or less sneak up on survivors. Sounds like something interesting to keep your eye out for.