>>58111990
In the grand scheme of things the rainbow bridge is a teeny tiny thing(essentially in pokeworld terms if you crossed the rainbow bridge in Celadon you would still be in Celadon when you arrived at the other end). Only the aqua line(which is only partially an underwater tunnel, there's still a pretty significant chunk of bridge above ground) actually crosses Tokyo Bay from central Tokyo to the region that in the pokeworld corresponds to Fuschia.