system
Given the following post, respond as if you're commenting on Reddit:
human
[Smash Bros.] How does Smash work?

Do they just wait in a lobby to battle or get taken from their worlds when they are chosen? Certain characters have show prior knowledge of Smash such as Ryu in this trailer saying "So this is Smash."? Do they remember Smash offscreen in their own worlds? Does Mario have flashbacks of being sliced by Roy's Sword or Olimar have Flashbacks of The Villager's Murder Stare? What about Metal Face? How is he Alive? How do Mario and DR. Mario Coexist?
gpt
Most this knowledge comes from the Subspace Emmissary campaign.

They have pretty clear knowledge of it, as we see Pitt watching from his home dimension. Most the competitor seem to enjoy the challenge of the battle, and see it as a good way to pass the time.