I'm not really sure what can be said about the nonspells, and there's a severe lack of material to compare with from the original works, but they're fun at least. The danmaku seems like something both characters might do for real.

The first spell establishes both characters' "inverted" abilities. Daiyousei's usually a Great Nature character, so her new ability has to do with... computers and stuff? Meanwhile, Koakuma apparently uses elements of darkness under normal circumstances, so she's going to kill herself using all that light. XD
The only nitpicky thing I'd mention is that the lasers stay even after Koakuma moves away, which seems a bit strange... That's so incredibly trivial, though. Really fun spell.

Daiyousei's solo nonspell is nice. While it doesn't match with what she normally does, I say that's a good thing because her original nonspell was really bland. It also shows the change in ability quite clearly, which is good, too. As for the second spell... well, I like how the nonspell transitions almost seamlessly into this. Nonspell-spell sets are always nice, in my opinion; I don't know why not many people do more of that. I would have almost called you out on cheapshotting the player with the instant changing of direction in the blue columns, but it seems the presence of the player will prevent the bullet from spawning, which is a relief. Though, this seems a lot like "Omiwatari that the God Walked", which is a nature-oriented spell...? I'll assume it was unintentional, but if that isn't the case, I suppose you get brownie points for the irony factor.

The third nonspell goes a bit back to her original nonspell, but that isn't bad. It keeps an original element though, which is good. Following up is the third spell, "Computerized Mare", which is... "Robot Unicorn Attack!" The curvy bullets from Daiyousei herself is a bit fast for some strange reason. Maybe it's because I'm getting distracted by the Akashic Record Player...

Next, it's Koakuma's turn. It's nice to see her start each wave of the nonspell with a great burst of light. Nice to play and refreshing to see.
The spell could be a bit less surprising. I wasn't aware of what was going on, so I was just grazing the falling bullets when they all exploded. The curving bullets from Koakuma herself might be turning a bit too much when they are far away, at the bottom of the screen. It might be hard to dodge, just saying.

The next Koa nonspell is pretty, but something about it gives me a feeling like it could be used by one of the fairies...

The lasers in the spell scare me a lot, I kept thinking they would stop at any moment. It's still nice, but it seems like an edit of an ice spell, which has nothing to do with Koakuma at all...? Well, it all comes down to interpretation, and a named spell card helps with that aspect. It does indeed look like a burst of light, which does seem anti-Koakuma. Nice.

Daiyousei's part of the final spell is a bit problematic -- it seems to have Yoshika syndrome. Koakuma shouldn't be that surprising either, but for some reason it is. I guess that's my fault for not remembering the previous spells.

Still, it's a great ending to a great script. Your scirpt utilizes really original ideas while tossing the original gimmicks out the window, but it doesn't matter because your danmaku is well executed and well balanced, making them really fun to dodge; this might as well be the original Daiyousei and Koakuma bosses. Everything was really visually appealing, but not in a way that was too distracting, either. Well done.