I think they would released "soul polymerization" instead of "super polymerization" tn the rewards as a support for wiseman. 'cause this Neos Wiseman card is so hard to summon.
If you mean the Manga exclusive "Soul Fusion" card, it would be a little bit broken. it would have to be at LEAST limited, as it would allow players to fusion summon with cards in their graveyard, causing- for instance- a 99999 atk/def chimeratech overdragon, etc.
There is no card called "Soul Polymerization", however. The card Jaden used to merge him and Yubel was Spiritual Fusion, and is garbage.
Super Polymerization doesn't help Neos Wiseman at all, and would quite probably be broken here. (Though I expect this new Jaden to have a skill that gives it, likely at 1k LP.)
Jaden and Yubel do fuse using Super Poly.
Spiritual Fusion was merely used to change the materials Yubel selected into Jaden himself and Yubel, which is a really huge asspull if you think about it XD
It makes sense given the rules of the dimension they were in. (Most of those dimensions seem to share similar rules to eachother, that differ from the "main" one.) Not even the first time a human and a monster spirit were merged in that arc (the three masked knights were a thing). Also, Yubel was fusing dimensions together with it at the time Jaden did that, so fusing 2 souls seems fine.
穂村 尊
Lazi
