Vandelay
Life is absurd. Lean into it.
Nah Doomsday gotta be on his own for the third movie. Now a Luthor/Brainiac or Luthor/Metallo collabo would be
See i wasnt the biggest follower of superman comics, but i did follow them around the death and rebirth series...i dont recall doomsday being that spectacular a villain other beating the shyt out of superman really being all that interesting of a villain....its been 20 year so forgive me. I see a storyline like this...and this is if i was david goyer and the studio was trying to coax me into writing some iustice league bs...
You know if doomsday is involved supes is gonna die or come close to it...doing that in the third/last movie would be to tdkr-ish.
In part 2, maybe doomsday is some relic/convict left over from after krypton blew up. Some how he makes it to earth, or lex finds his body and brings him to earth where they work out some partnership for profit/domination/revenge whatever...
He and supes get into it...and supes ultimately wins but is defeated and assumed dead. This could play into the whole scenario where clark is constantly hiding his identity disappearing off the face of the earth.
Enter movie 3 and the jl tie in...in supes absence a bunch of other knockoffs pop up...in addition, other superheroes, flash, batman, perhaps green lantern or wonder woman could make semi cameos...dunno how "realistic" they would be, but would pop up because supes "inspires" the world to change like both his pops wanted. But some unknown force...a darkseid perhaps or maybe the cyborg superman from the rebirth comes along who these replacements cant handle, and force supes out in the open...maybe save darkseid fo the jl movie...
For the record i dont wanna see a jl movie...but maybe this is how u could tie it in.