Well, with Ultra Instinct, Goku would be able to react extremely quickly to the DC heroes' powers. For instance, when facing Flash, who is super fast, Goku in Ultra Instinct might be able to match his speed or even anticipate his moves better. This could lead to a mutual respect between them as they test each other's limits.
Ultra Man Story often involves the heroic deeds of Ultraman in protecting the Earth from various monsters. Ultraman uses his special powers like the Specium Ray to fight against the threats.
In Ultra Man Story, Ultraman is the central figure. Besides him, there are often human characters. These human characters play important roles, sometimes as scientists who study the monsters or Ultraman, and other times as soldiers or ordinary people who get caught up in the battles and try to help Ultraman in their own ways.
Definitely not. Spider-Man is a prominent figure in the Marvel universe and has no place in DC Comics. DC and Marvel are separate comic book entities with their own distinct characters and storylines.
Maybe Goku gets mixed up in the events of the Injustice storyline. He could initially be confused by the alternate version of Superman who has gone bad. Goku, with his pure heart and Ultra Instinct, might try to bring the corrupted Superman back to the light. This could lead to some intense battles with the Injustice League as Goku tries to set things right.