Unfortunately, the new Pokemon release will not contain any Pokemon not in the Galar Dex. This means that not only is there no national dex, but you can't even transfer your old Pokemons into the game. Obviously this also affects the Romhacks which will not be able to provide a full Pokemon experience.
Not a direct source, but: https://www.reddit.com/r/pokemon/comments/bzfdoz/with_the_news_that_only_the_galar_dex_will_be/
EDIT: Better source (thanks to leafeon34): https://www.engadget.com/2019/06/11/pokemon-sword-and-shield-limited-transfers/
Not a direct source, but: https://www.reddit.com/r/pokemon/comments/bzfdoz/with_the_news_that_only_the_galar_dex_will_be/
EDIT: Better source (thanks to leafeon34): https://www.engadget.com/2019/06/11/pokemon-sword-and-shield-limited-transfers/
Last edited by pworld,
, Reason: Better source added