Yeah, I used to have trouble with posting at first. Those were what they pretty much looked like.
In my opinion, and I know we all have said this, The explination of how Chomper got to the Great Valley again would make a nice plot for another movie. Of course, in a lot of fanfictions, the most logical reason is his parents helped him cross the landbridge from their island, and they kept walking until they found it, but then again that's a fanfiction and nothing is ever true in those.
My guess is the movie series might end with Chomper and Ruby arriving at the Great Valley, but then again, the only reason why I don't see this happening is because they explain how the two get there in the TV series.
However, the TV series messes up logic in this, because Chomper moved to the new island after the second movie, so how could he magically appear back in the Mysterious Beyond? This would also argue that Chomper should not know Ruby yet, but like you said it's a kid's show so the creators must have thought they didn't need to make this logical.