I am also sharing this with the community and everyone is more than willing to share.
Metroid Calamity Boss Ideas
Prehard Mode: Botwoon, Desert Geemer Queen, Sky Waver
Hard Mode: Astral Serris, Glowing Mushroom Spore Spawn, Sulfur Draygon, Ecto Phantoon (dungeon)
Post Moonlord: Profaned...