CROWN TUNDRA:
No new Gigantamax forms or Galarian forms apart from the Legendary Birds and Slowking, which is Dark/Psychic type and is Peony's signature Pokémon.

The only new Pokémon that haven’t been revealed yet are a pair of brand new Ultra Beasts. They are version exclusive:

Pokémon Sword: A skeletal horse with smog surrounding it. On top of its back it has a humanoid skeleton with blade-like arms. It sort of resembles the nuckelavee of Scottish myth. Poison/Ghost type.

Pokémon Shield: A monstrous-looking lion resembling a cross between a manticore and a chimera. It has a large shield for a mane, and flames for eyes. Dark/Fire type.

Depending on the version you picked, one of these Ultra Beasts will fuse with Calyrex in the events of the Crown Tundra, using a special item from the Ultra Space that allows them to do so. You’ll eventually fight the fused Calyrex as the final boss of the expansion, and you’ll have to use another item made by Peony that will allow Calyrex and the Ultra Beast to defuse. After the main story, you’ll be able to catch them separately, fusing them and defusing them as you desire.

There will be no more DLCforSwordandShield after the Crown Tundra.