People seem to be liking my complicated and slightly radical version of Ninjagos oni so how about an explanation on the different subspecies of oni I’ve made?
Traditional oni: original oni they inhabit the first realm mostly and have medium length fur they exhibit all types of patterning duplication amount varies a lot.
Frinaz oni: typically inhabit colder environments they have longer and thicker fur and have the “feathered” feet that you see on horses on their back legs they are more likely to have all duplications or at least most. they tend to have bone like patterning or speckling or sometimes splotches and tend to have more patterning than others.
Fiara oni: almost always live in hot arid environments and are strictly nocturnal often having more blotchy patterning especially on the face and it’s not uncommon for them to have a full fully white or almost completely white face. They have the lightest skin tone for an oni often appear in gray instead of black unlike all other oni they have almost no fur with some having none at all, but usually they have manes and tails and some fur covering the armpits, elbows, crotch, and the lower middle torso they usually have less duplications than other oni
Wiata oni: tend to live near large bodies of water or wetlands they have the least amount of marking coverage and tend to have splotchy, sharp, or swirly patterns. they have short fur and almost always have straight hair they have slightly webbed paws and tend to have sharper teeth and claws.
Tiamior oni: sometimes called the domestic oni usually reside close to humans or humanoids have a stronger tolerance for non-humanoid dragon or oni meat tend to have less duplications and their markings are often odd or non-symmetrical they come from other species interbreeding with oni multiple times within a line they have shorter fur and are the only oni that have extremely curly body fur although not all of them have it they are more prone to health issues and may not have all organs duplicated or might have a half duplication like having three arms instead of four or one and a half hearts the most common duplication glitch is having three kidneys instead of four or two 
I got my ideas from a mix of head cannons coming together, most of which being me head cannoning a bunch of characters to be oni here are said characters types of oni:
Lloyd, and Garmadon: mixes between traditional and frinaz oni
Fsm Harumi and overlord: traditional
Mystaké: frinaz
Cole, his mother, and Arin: tiamior
Ultraviolet and killow: fiara
Sora: wiata and tiamior mix
I might draw all of them in their oni forms at some point for better representation, but this is what I’ve got for now.
Also, this is for an au where oni are the main focus and dragons kind of just stay in the background so FSM is just a very strong oni with a rare element who happens to be capable of putting the overlord in his place.
