Medi of the Diamond Clan has posted a request regarding a pokémon that helped her long ago.
The Request
This request is only available if you have Pokémon Sword or Pokémon Shield save data on the same user account on your Nintendo Switch that you are playing Pokémon Legends: Arceus with. Check on the blackboard in Professor Laventon's office in Galaxy Hall in Jubilife Village to accept this request.
Speak with Medi
Go to Fieldlands Camp in the Obsidian Fieldlands and speak with Medi to proceed.
Go to Floaro Gardens
Go to Floaro Gardens, west of Fieldlands Camp, and enter the brown circle at the end.
Catch Shaymin
If Shaymin runs away, you can either rest at a base camp in the Obsidian Fieldlands to try to make it reappear, or just go to Jubilife Village and come back to Obsidian Fieldlands to make it reappear. Catch Shaymin to proceed. If you battle it, try reducing its HP and inflicting status conditions, then throw Ultra Balls (or whatever types of Poké Balls you have available) until you catch it.
Reward
You get 1 Grit Rock.