Yeah, these bosses are so well-done, I wonder how long the people of the game took to make these custom bosses functional. Nonetheless, I put a lot of effort into making this video.
Well, Pepsi Man in Pepsi Zero uses his own theme, while Magmatron and Elec Spine don't have their own boss themes, since the Null and Void level is using its own theme from 20XX. If anything I said is wrong, then maybe you possibly try to correct me, who knows.
There IS a possibility of Fighting Fefnir to be a blob version of him, much like Zero on how he looked in MaGMML1, 2 and Remastered. It's a very low chance of him to appear in blob form, so keep on rematching him and eventually, the blob version of Fefnir will appear.
Time sure flies by pretty fast, huh. This game did get released in June 2020, so when we reach that month again, it'll be officially one year for Episode Zero.