As part of the Pokémon Presents broadcast this afternoon, The Pokémon Company just revealed that both The Pokémon Trading Card Game from 1998 and Pokémon Stadium 2 from 2000 will be joining the Nintendo Switch Online game library.
While you will be able to play The Card Game with just the basic subscription through the Game Boy library, you will need the Switch Online + Expansion Pack add-on to be able to access Pokémon Stadium 2, as that is part of the Nintendo 64 library that is offered as part of that upgraded subscription.
Assuming you do have either subscription, you will be able to play these games as soon as later today, as both are being added on August 8, 2023.