I come to say something important (surely spoiler), that the true villain of the sequel It's not Yesss or Double Dan, is the own Wreck-It Ralph getting into mess again. And I have been looking very carefully at the scene where they are being chased by a wave of viruses.
Apparently, in some of them, had a similar shape to Ralph, that is, that literally the virus is formed by a mass of clones of Wreck-It Ralph out of other games and other things. This could explain the question asked by Rich Moore in April 2014: Will there be other Ralphs, there will be more modern Ralphs?
It also explains why Ralph goes to the Darknet and meets Double Dan, for what we see in the background, is a secret laboratory that manufactures viruses that can threaten the Internet.
Maybe Wreck-It Ralph went to see Double Dan to ask him to do something that forces Vanellope to be her best friend again, which also explains why the Japanese trailer shows Slaughter Race bugging and disappearing.
At the moment this is just information that I have theorized, We don't know exactly if this really happens in the movie.