Pikachu's Big Mysterious Adventure
Originally released in the middle of the Sinnoh League this Pikachu short needed to be relocated. The opening shot features a built up city on the edge of a body of water, which doesn’t match what gets seen of either Sunnyshore or Lily of the Valley Island.
Since DP181 shows the ferry stopping along the way for supplies,
it’s possible that this unnamed city is another one of these stops, so lets
place it in that window.
Source: serebii.net