Neo-Psychedelia is one of my fav uncommon genres. There's several songs that fit the genre that are fairly known, but as a whole I don't really see it around that much. Same goes for Ska, which I used to listen to all the time a few years ago. I also listen to a lot of power metal and alternative rock.
I cant link anything right now since I'm actually supposed to be cleaning my house and keep getting distracted, but I recommend bands like Hot Sugar for neo-psychedelia and then Streetlight Manifesto and Reel Big Fish for ska. Blind Guardian is my quick metal rec and one of my favorite bands of all time (with grand parade probably being my fav song right now. They're most known for their song, Battlefield, which was used in the metal version of Robot Unicorn Attack), and then Jukebox the Ghost for alt rock because they're greeeaaaaat. Just real quick recs before I get back to work.
(although as an add, I don't even know what counts as "uncommon" anymore since I tend to just listen to whatever and my area actually has an alt rock station so I end up just assuming anything that's not rap, pop, or country is probably uncommon, even though that may not really be the case)