A lot.
But no, really. My main 2020 plot was always intended to be smaller in size than The Curse despite the increased stakes, but even with that in mind, the massive plot logjam we wound up with in the second half of the season, one of the most intense ever despite the low overall post count of the season, ensured I had to keep Dark Matter trimmed down to the basics. If it hadn't been for the plot's collaborative nature, Dark Matter might not have left much of an impact, but the events from other users kept the plot going when I was unable to squeeze in any events (I managed just one Dark Matter plot in July, one in August, two in September, and the three-day finale in October.)
As a result, a ton of content was cut from the plot, as I scaled even further back from my original plans. Most of it was Kirby-related content I cut in favor of focusing on alternate dimension Kobbers, as I felt that was on the whole the more interesting angle. Kracko and Miracle Matter were non-negotiable, however - these two Kirby bosses are near and dear to my heart. Let's go into why.
Miracle Matter is the easy one to explain. Aside from the Kirby 64 connection, Miracle Matter was also set up earlier in the year as the method to get Bree to slip in a Dark Matter representative, that being Miracle the Ditto. I couldn't very well cut Bree's only representation in the plot, and really didn't want to, either, considering the status I was planning to assign to Miracle as being the most powerful of the vassals due to the Dark Star Kobbers being unable to keep up with its' rapid shapeshifting. (Side note: We would have had an extra round of combat against Miracle where she turned into various Kirby bosses I'd had to cut from the plot, but I cut that round of battle as well when people figured out her deal early in the fight.)
Kracko is a personal one. On another forum I used to frequent way back before ZFRP took off, I was the author of a Paper Mario-themed fanfiction that, while juvenile and crude by my current writing standards, I will always owe a debt to, because it was how I first got the courage to start writing and posting things online and joining a community instead of being at the fringes. The fanfic was received well by my peers, to the point I'd built up a minor cult of personality around myself. One of the most ridiculous results of this was a user joining the forum with a username nigh-identical to my own, which they took specifically out of admiration of me. This was flattering and all, but the resulting name confusion bothered me, and rather than ask this person to change their username, I did my own change, and shifted from one minor Nintendo boss to another, going under the username "Kracko" for a while in the mid-2000s. As a result of using him as my name and avatar, I felt a connection to this silly recurring Kirby boss, and so when I decided to do a Kirby plot, I knew I simply had to integrate him into the proceedings.
So, about those cut characters...