User blog comment:Epzilon/The Eleven Supernovas come to Bleach?/@comment-18812574-20150923235702

Well I'm not here to be a nay-sayer or anything but... I just can't help but ask: Why do we need these supernova again?

We have the Royal Guard, who haven't been given much attention in fanon in general: but there is the possibility there. These guys are insanely strong. Let us not forget Ichibei vs. Yhwach, that is.

We have the Espada, who were meant to be seen as major opponents in canon and, under the hands of a skilled author can be just as much of a threat.

We have the Yonkō, which you already mentioned.

We even have the Four Rukongai Kings, who are meant to be seen as powerful/influential enough to where the Gotei are like: "Yeah, we'll just let them be."

In my opinion, the ingredients are already here, just wandering around in random places.

If you REALLY wanted to do this supernova thing, I might suggest something along the lines of a databook: so maybe the Soul Society has compiled a list of the most dangerous/powerful elements/individuals outside of the Gotei 13 and wants to keep tabs on them. If these guys ever WERE to unite under one name/organization, that is, I imagine the Gotei would be very, very concerned and probably try and take action to prevent such an alliance from forming.

But to be honest, I don't know why a list as you described it here is necessary, besides being able to brag about "my [Zanpakutou] being bigger than yours."