Best Answer: Y-Comm is a new feature introduced in Pokémon Sword and Shield that serves as the place where you can trade Pokémon, have Link Battles, as well as send and receive notifications about participating in Max Raid Battles. All of these use either online or local communication. Any online communication requires an active Nintendo Switch Online subscription.
How do I access the Y-Comm?
The Y-Comm is simply another option in the game menu. You can access it at any time by pressing the Y button on your Nintendo Switch. Once it is open, you will see a feed with all other connected players. The side menu lets you navigate through different sections in Y-Comm.
What are Max Raid Battles?
Max Raid Battles are a new gameplay element in Pokémon Sword and Shield. With Max Raid Battles, players can team up with up to three others to take on wild Dynamax Pokémon in the Wild Area. As you investigate Pokémon Dens, you will encounter different species of Dynamax Pokémon, so make sure to explore everything!
These wild Dynamax Pokémon are no joke, either. During battle with these Dynamax Pokémon, there is a chance that they could do multiple moves in a single turn, neutralize your own Pokémon’s abilities, remove all stat changes that are currently in effect, or put up a barrier that prevents most damage. These battles will require more teamwork and strategy to overcome, but the rewards (catching the defeated Dynamax Pokémon and useful items) are worth the time and energy.
If your Pokémon gets knocked out during a Max Raid Battle, you can continue to cheer your teammates on. The key to taking down barriers is by repeatedly attacking them, and just giving it all you got.
What is Dynamax?
Dynamaxing is a new game element introduced in Generation VIII. With Dynamaxing, it is a temporary transformation of a Pokémon that increases their size drastically, increasing their stats, and changing their available moves into Max Moves.
Players can Dynamax their Pokémon as long as they have the Dynamax Band item. Dynamaxing can only be used once per battle and lasts for three turns only. The Max Moves for your Pokémon are dependent on the moves that it knew before Dynamaxing, and Max Moves are, in general, much more powerful than the regular moves.
During a Max Raid Battle, the opposing Pokémon starts in Dynamax form and does not revert. Players start in their original form, and only one trainer’s Pokémon may Dynamax in the battle for three turns. Certain Pokémon can achieve a special kind of Dynamax form, known as Gigantamaxing. Pokémon who can Gigantamax have a different appearance from their regular form, are larger and have an exclusive Max Move called G-Max Move.
Y-Comm can also be used for trades and Link Battles
The Y-Comm is the central hub for communicating with other Pokémon Sword and Shield players. You’ll be able to trade Pokémon with each other here, whether it’s with friends you know or online with strangers from all over the globe. If you want to Link Battle with friends, whether locally or online, the Y-Comm is the place to go for that as well.
Usually, the Link Trade lets you trade Pokémon for something specific that you are looking for. A new feature in Pokémon Sword and Shield is the Surprise Trade, where you put up a Pokémon for trade and are randomly matched with someone else, getting a completely random, surprise Pokémon. You never know what you may end up with from here!
Y-Comm trades can happen in the background
Sometimes the process for Y-Comm trades can take a while to get paired up with someone. Fortunately, you can keep adventuring or battle while the Y-Comm is setting you up with someone. Once the trade is complete, you get a notification letting you know.
Pick up your Swords
Pokémon Sword features the legendary Zacian and will feature exclusives like Farfetch’d/Sirfetch’d, Deino/Zweilous/Hydregion, and Jangmo-o/Hakamo-o/Kommo-o.
Pick up your Shields
Pokémon Shield features the legendary Zamazenta, and has the exclusive Galarian Ponyta/Rapidash, Larvitar/Pupitar/Tyranitar, and Goomy/Sliggoo/Goodra.
Source of the article – iMore