The Pokemon Company have issued an apology following Dewgong's appearance in Episode 4 of the Twilight Wings anime.
This doesn't really seem like something to apologize for, given Dewgong is a perfectly likeable Pokemon. However, the Gen 1 classic is one of many species that isn't in the Galar region Pokedex. This is something that didn't go over fans head's.
"[Apology] In the web animation 'Tsubaki no Tsubasa', some Pokemon that did not appear in 'Pokemon Sword Shield' appeared. I am sorry for making a misleading expression," the official Japanese Pokemon account tweeted. This translation is a little rough around the edges but we can see that the Pokemon Company admit its inclusion was misleading.
— ポケモン公式ツイッター (@Pokemon_cojp) April 24, 2020
Dewgong to be added?
200 currently unavailable Pokemon will be coming to the Galar region as part of the Pokemon Sword and Shield expansion pass. While few have been confirmed so far, Dewgong's appearance indicates the Sea Lion Pokemon will be one of them.
Other Gen 1 species have been confirmed however, including Chansey and Nidorino. Other notable additions are Azurill, Elekid, Garchomp and Magnezone.
Presumably all their respective evolutions will also be added. They will spread across both the Isle of Armor and Crown Tundra DLCs. The latter will add a lot of missing legendary Pokemon, too.
Sword Shield anime
The web based anime is being used to promote Pokemon Sword and Shield. An anime depicting various happenings around the Galar region is an excellent way to get more fans engaged with the Nintendo Switch game and hopefully get them to buy it.
The episodes may only be six minutes long, but fans have already been eagerly anticipating them. New episodes are releasing on a monthly basis and there are seven of them scheduled.
Episode 4 actually focuses on Milotic, but it was Dewgong's brief sighting that actually got the community talking. The closer we get to a National Pokedex, the less likely it will be that instances like this happen again.