2) Glory O'Brien's History of the Future by A.S. King. All of A.S. King's books are weird, to the point that I usually don't understand them, but this one may be the most so. A YA magical realism, like all of her novels, it tells the story of a troubled teen girl who drinks a liquefied bat and starts seeing visions of a dystopian future that she then tries to prevent. But, like, weirder than that. It wasn't my thing, but it works for plenty of other people. Another one by A.S. King that I do like is Still Life with Tornado.
4) Hit by Delilah S. Dawson. This is a hecka-weird near-contemporary YA dystopian, where credit card companies take over the country and force people to assassinate each other in order to "pay" off their debt. It's strange enough that I'm not totally sure how to feel about it--but I did enjoy it.
5) The Raven Boys by Maggie Stiefvater. Maggie's Raven Cycle is extremely popular and quite unusual. Once again, I don't really know how to describe it, but it's basically a YA fantasy about a group of private school boys looking to awaken an ancient king and the girl who joins them. It also has prophecies, ghosts, sentient forests, assassins, fae lines, weird dreams, and a lot of unique characters. Check it out!
6) Jackaby by William Ritter. This YA paranormal mystery is often referred to as "Sherlock meets Doctor Who," but I'd argue that it also has aspects of Harry Potter and Supernatural--basically all those big fandoms. Additionally, it has a historical setting. Jackaby is a haphazard jumble of good things, and I enjoyed it quite a bit. I haven't read the rest of the books in this series, but I'm excited to.
7) Beauty Queens by Libba Bray. This YA contemporary is like Lord of the Flies--but featuring a group of teen beauty queens. It's incredibly strange, satirical, and snarky, and it features a multimedia aspect as well. A number of social justice issues, particularly feminism, are addressed. I'd recommend this novel for mature readers.
8) My Lady Jane by Cynthia Hand, Brodi Ashton, and Jodi Meadows. This is kind of an alt-history novel that adds an unusual fantasy aspect to the story of Lady Jane Grey, a.k.a. England's Six Day Queen. So, like, YA historical fantasy? But with an added measure of fun and oddity. Give it a try!
9) Scythe by Neal Shusterman. This YA sci-fi features a utopian world, which makes it a weird one from the start. Utopian worlds are hard to work with, because they mess with the reality of human suffering and conflict. In this world, there is no natural death, so in order to avoid overpopulation, a group of people called Scythes are charged with killing a certain quota of humans each year. It's really unnerving to think about what it would be like if death wasn't a certainty. Like, you start wondering what the point of existence would even be. It's a good novel to check out, and I'm super interested in how the sequel turns out. (Also, I love Neal Shusterman, so.)
10) The Girl from the Well by Rin Chupeco. Like A.S. King, Rin Chupeco specializes in weird, though she's more of a YA horror author. This novel, her debut, tells the story of a young-but-ancient and murderous Japanese ghost, in the vein of The Grudge or The Ring, who attaches herself to an unusual teen boy. They're drawn into a whole dark world of ritual and magic. Though I sometimes struggle to comprehend it, I like Rin Chupeco's writing. Give this, and her other books, a whirl!