Ok first thing I agree with others about the Vinsmoke family powers have been foreshadowed before. We know from chapter 840 that they have Exoskeletons just like insects and some other animals because Judge messed with their genes, so this scene from Jaya Arc is maybe a foreshadow to their powers….
We know that they are humans whose genes were messed with to make them stronger. These are the ones I think they used, except for Niji’s.
As we know Reiju’s powers are based on a moth or a butterfly. If you don’t know many Moths and Butterflies make up a group called Lepidoptera which consists of the Monarch Butterfly and the Garden Tiger Moth that both can help produce poison which comes from the toxins in plant species they eat. Which would explain her beingPoison Pink epithet.
Plus if you look at the pattern on the moths in the picture they look a lot like Reiju’s outfit when she is first introduced.
Now on to Ichiji. We haven’t seen any of his powers at all, but I think he is the Centipede. Now Centipedes have a special type neurotoxins that effect the nerves in different ways. Some can even cause paralysis.
I think this is the cause for his epithet of Sparking Red it isn’t electricity or flame that a lot of people think it is. It is a neurotoxin that attacks your nerves sending a shock through your entire body and can cause paralysis of certain areas.
For Niji I agree with @OneWorldHD idea on youtube that he is based on the oriental hornet. Which if you don’t know has a yellow strip on its exoskeleton to absorb sunlight to use to generate electricity. It also says these stings can be quite painful for humans, and their stinger doesn’t come off so they sting many times. Which would explain his Electric Blue epithet.
Also if you look at Niji’s kick it looks like he is getting stung when he gets kneed by Niji, also the electricity flowing out after the hit makes it looks more like it. Also if you haven’t noticed the sound affect above Bzzzzt is the sound a bee or hornet makes.
Last but not least is Yonji. He is the other animal from the foreshadow who has an exoskeleton, he is the Tarantula. Now first, a winch is a mechanical device that is used to pull in (wind up) or let out (wind out) or otherwise adjust the “tension” of a rope or wire rope (also called “cable” or “wire cable”).
Which I think references to tarantulas and spiders and use them to move, also yes tarantulas do make webs they just don’t use them to eat and produce them from their feet/legs. Which I think fits the epithet Winch Green. Would also be cool example to be used for the name.
All of these if you don’t know are nocturnal except for the oriental hornet but thy build their nests underground in the dark so all of them live in the dark which connects to the how the Vinsmokes are in the underworld
Theory by Onepiecefan9867