I guessed that the cameos were good, but I wanted to have the evidence up since I'm considering nominating them.
For the record I'm not planning on nominating either the 90s Flash or Superman movies, but included them for completeness. I'll go ahead and do evidence for them.
90s Flash In last year's crossover, called Elseworlds, the Monitor attacked Earth-90, the Earth of the 90s Flash. Barry fled and ended up on Earth-1. He warned CW Flash and the others about the Monitor. When he attacked the Monitor he disappeared.
He later reappeared this year for Crisis on Infinite Earths. The Anti-Monitor had captured him and was forcing him to run on a treadmill that was powering an antimatter canon that was destroying the multiverse.
Now, since season 1 of the CW Flash there had been a newspaper from the future that stated that the Flash would die on in a Crisis.
CW Flash prepares to go on the treadmill, where he would run it in reverse to destroy the canon.
However, 90s Flash instead offers to make the sacrifice. He gets back on the treadmill and runs until he dies, successfully destroying it. They show a clip from his show as he dies.
Superman They are told they need the Paragons to save the multiverse. These are the seven greatest heroes in existence. Their search first takes them to the Smallville Earth, but that Clark isn't a paragon.
They then end up on the world of the Superman movies, with Brandon Routh resuming his role as Clark from Superman Returns (while Returns was only explicitly a sequel to 1 & 2, he also mentions the events of 3).
We find out that most of the Daily Planet staff were killed in an attack by a madman from Gotham.
The Lex Luthor from the Supergirl show followed them and uses a magic artifact to make the movie Superman fight the CW Superman. The others eventually get the book back and end the fight.
Movie Superman joins the heroes and goes to Arrowverse Earth-1. He spends the next two episodes with the heroes until the anti-matter wave hits Earth-1. In a last ditch effort the paragons are teleported away to a place outside of time.
When they get there Superman finds himself in pain. He dies in the arms of CW Supergirl. Lex then appears in his place, having used a piece of the artifact to take Superman's place as a paragon.
Later, after the multiverse is restored, we see Routh's Superman flying on his own Earth.
Re: Arrowverse
For the record I'm not planning on nominating either the 90s Flash or Superman movies, but included them for completeness. I'll go ahead and do evidence for them.
90s Flash
In last year's crossover, called Elseworlds, the Monitor attacked Earth-90, the Earth of the 90s Flash. Barry fled and ended up on Earth-1. He warned CW Flash and the others about the Monitor. When he attacked the Monitor he disappeared.
He later reappeared this year for Crisis on Infinite Earths. The Anti-Monitor had captured him and was forcing him to run on a treadmill that was powering an antimatter canon that was destroying the multiverse.
Now, since season 1 of the CW Flash there had been a newspaper from the future that stated that the Flash would die on in a Crisis.
CW Flash prepares to go on the treadmill, where he would run it in reverse to destroy the canon.
However, 90s Flash instead offers to make the sacrifice. He gets back on the treadmill and runs until he dies, successfully destroying it. They show a clip from his show as he dies.
Superman
They are told they need the Paragons to save the multiverse. These are the seven greatest heroes in existence. Their search first takes them to the Smallville Earth, but that Clark isn't a paragon.
They then end up on the world of the Superman movies, with Brandon Routh resuming his role as Clark from Superman Returns (while Returns was only explicitly a sequel to 1 & 2, he also mentions the events of 3).
We find out that most of the Daily Planet staff were killed in an attack by a madman from Gotham.
The Lex Luthor from the Supergirl show followed them and uses a magic artifact to make the movie Superman fight the CW Superman. The others eventually get the book back and end the fight.
Movie Superman joins the heroes and goes to Arrowverse Earth-1. He spends the next two episodes with the heroes until the anti-matter wave hits Earth-1. In a last ditch effort the paragons are teleported away to a place outside of time.
When they get there Superman finds himself in pain. He dies in the arms of CW Supergirl. Lex then appears in his place, having used a piece of the artifact to take Superman's place as a paragon.
Later, after the multiverse is restored, we see Routh's Superman flying on his own Earth.