Including new forms or mega evolutions.
Bonus points for “how to obtain” if relevant
https://www.polygon.com/pokemon-legends-za-plza-mega-dimension-dlc-hyperspace-pokedex-list/ This link leads to a complete Mega Dimension Pokedex.
Darkrai is obtained in the main quest "Hyperspace Survey 6" while all other legendaries (I just killed Darkrai, so this is a guess) are obtainable after that, including Rayquaza. Mega Lucario Z is also available after the Darkrai battle, and Mega Garchomp Z is currently unavailable, predicted to pop up in some event in the near future.
Happy to help, but I can predict with my psychic powers that a better answer will pop up soon.
