Update Jan. 20
The full abilities have been datamined for each new Pokémon but once again take it all with a grain of salt until Pokémon Home becomes compatible and you can see for yourself. The table below has been updated to all 28 new Pokémon and their abilities.
Pokémon Legends: Arceus is completely changing the traditional formula of the Pokémon franchise, and the most significant overhaul is the battle system, along with removing a few more series staples. Pokémon abilities are removed altogether, very much like Pokémon GO and the Pokémon Let’s Go Switch titles.
Even though the Pokémon abilities in Arceus aren’t available, they still exist within the game’s data. Meaning all the Pokémon in Pokémon Legends Arceus are still assigned abilities by their species/type, but they are unused. The reason behind this is Pokémon Home, which is compatible with Arceus, yet coming later on in the year.
The hidden data will be applied when relevant, such as when trading these Pokémon between different games, so Pokémon goes without an ability. Here are the leaked abilities for the new Pokémon in Pokémon Legends: Arceus.
For more on Pokémon Legends: Arceus, Pro Game Guides has you covered.