A new trailer recently released for the upcoming game, Pokemon Legends: Arceus. In this trailer we’re introduced to the Diamond and Pearl clans and the Ginko Guild. The Ginko Guild is a team of merchants that travel the Hisui region, finding people to trade with. You’ll come across these merchants on your journey and be able to buy and sell items with them, similar to Poke Centers in previous games.
Ginter – Ginko Guild Leader

The Ginko Guild Leader, Ginter, keeps the guild together but doesn’t travel as much. He’ll sell you more rare items that he finds across the region compared to other merchants.
Volo

Volo can be found traveling across the Hisui region and sells you less rare, but essential items. If you run into a merchant, no matter where you are, it’s most likely Volo.
What Do Merchants Sell?
What a merchant is selling depends on who you’re trading with but in the trailer we see the merchant selling several consumable items. They sell berries, which can be used to heal your Pokemon but also to attract wild Pokemon’s attention by throwing a berry near it. Bugwort, which is a healing item but can not be used on Pokemon because it’s so bitter. This will most likely be an item you can use on your Trainer to restore HP. Other items sold can be used to craft things or have status effects like strength buffs.