Having characters from apocalyptic futures might be a bit of a stretch, then you remember that Fuse is declared to be a master of many forms of science and technology, both of which have been used in CN shows to time travel. It's possible that he attacked the bad futures of both Jack and Finn, and dragged their heroes and villains into the 'main' timeline to compensate. This may also relate to the general absences of E.V.O's, if the Generator Rex timeline is also one of these bad futures, along with other elements and shows that don't quite have areas tied to them in game (I.E, any show that doesn't have areas from their show present as areas solidly placed in the map.)
Alternately Jack, Scotsman, and Demongo ended up time traveling back in a somewhat botched Aku disposal operation that mostly, if not completely worked.
With Ben 10 moved to his 15 year old self upon release, we actually have a chance of a connection between the Power Puffs and Ben. Namely, that the PPG would have been active around the time Ben got the omnitrix as a 10 year old. The heroes that Ben wanted to be like with the watch, hence his trademark Chronic Hero Syndrome, were very likely the Power Puffs themselves.
In the Ed, Edd, n Eddy episode 'Who Let the Ed in', Ed had an imaginary friend named Jib, who Eddy Put on a Bus at the end of an episode. In this world, it is not hard to imagine the bus went straight to Fosters, and familiarity with the location likely explained why the went there for boxes to build the Cul-De-Sac fortress.
Due to artistic issues with making them not look creepy, no funny animal characters are in game with the exception of Courage, who does look somewhat creepy. However, then you remember that Courage's show was all about creepyness and horror, and you see why he was allowed to slide where the comedy based Lazlo and Cow were not.
We only see a city, it's suburbs, wild areas, and the Darklands status. Lest we forget, many Cartoon Network shows tended to travel around. Even with Ultimate Universe esc changes, one has to wonder who is being a hero elsewhere? Beyond whose protecting the areas, just what is the wider battlefield like?
As far as it is aware, Sector V seems to be the leaders of the in-story KND. Then you remember that the Moon base was attacked in the manga, where the leadership of the KND tends to be, and we haven't seen Numbahs 362 or 86 around...
Grim can resurrect fallen player characters, but there seems to have been several casualties among the heroes after the battle of Tech Square. It would be weird if Grim forget to revive people as important as Blossom, Bubbles, and Ben...or perhaps Fuse has ways of taking them out that the grim reaper can't do anything about.
