How to get the Super Rod in Pokémon Sword and Shield

Leafeon and Glaceon's evolution methods have been changed. Leafeon now evolves by Leaf Stone and Glaceon now evolves by Ice Stone.

Umbreon and Espeon evolve through night and day as they did before, however it's worth mentioning that they evolve depending on what the actual location's sky is doing -- some towns have a fixed time of day, and the evolution will reflect that, even if it doesn't match up with the real world time on the Switch console itself.

If you want a Sylveon, it needs at least 160 friendship/affection and to know a fairy-type move. If you want an Espeon or Umbreon, it needs at least 220 friendship/affection and must not know a fairy-type move. See this answer for more information on the changes made to friendship/affection.

Isle of Armor

In the Isle of Armor DLC, there is a mini-game in which you are tasked find Alolan Digletts throughout the island. By collecting these Diglett, you will be given various Alolan forms (as well as a Kantonian form and Alola starter) as rewards for returning them to their owner.

Base Version

You cannot obtain Alolan forms in the base version of Sword and Shield, but you can by transferring Pokemon into the game via Pokémon Home (as long as the base form exists with in the Pokedex) or by trading with others players who transferred them from Pokemon Home

Alolan forms do existin the Galar region, as Alolan Meowth can be found in one of the camps. This camp is located on Route 7, and is known as “Renee’s Camp”