Midbosses never get any love, so here we go. When Dodonpachi spawns a midboss or boss, those get some preferential treatment when it comes to memory space. I think most people consider that there are 4 midbosses in the game, but some of the destructible structures get the same preference. All the midbosses got edits, and one of those structures did, too.
Midboss 1: New bullet pattern
Midboss 2: Turrets spin ~twice as fast
Midboss 3: Bugfixed bullet pattern
(I actually don't think the original campaign mode fixed
this bug, but I can't really leave it there in good conscience. On P1 side, in loop 2, the secondary bullets would be on the same trajectory as the parent, just slower. They're meant to have different angles instead of different speeds (or, at least, that's my take on it!). It's a bit hard to see, but just look for pairs of the same size bullet, with one following the other, on the original gif. Some of the fastest ones are easiest to notice. That behavior isn't present on the second gif, the bullets are always flying in different directions instead.)
Also, if you time it right, you get big stars from the big bullets now!
Midboss 4: Upgraded bullet pattern
(animations here are loop 2 since I think it looks even cooler)
Structure (from 5): Reload speed is twice as fast, and it opens/closes faster too