Legends: Arceus rewrote trade evolutions entirely. The Linking Cord, Black Augurite, and Peat Block let you evolve trade Pokemon without finding a trade partner. Hisuian forms have unique conditions. Stantler evolves into Wyrdeer by using Psyshield Bash in Agile Style 20 times. Evolution is triggered manually from the satchel menu.
They don't, at least not the traditional way. Every Pokemon that normally needs a trade to evolve can instead use an item from your satchel. The Linking Cord handles Haunter, Kadabra, Machoke, and Graveler. Scyther uses a Metal Coat directly without trading. This was the first game to fully remove the trade evolution requirement.
Stantler needs to use Psyshield Bash in Agile Style 20 times. The count carries across battles, so just spam it whenever Stantler is in a fight. After 20 uses, the evolution prompt appears in your satchel. Agile Style specifically; Strong Style doesn't count.
Three ways. Buy one from the Trading Post in Jubilife Village for 1000 Merit Points (earned from returning lost satchels). Find them as random drops in Space-time Distortions. Or complete Request 64 ("Getting to Know Ghosts") for a free one. The Merit Point method is the most reliable if you're actively playing online.
Give Ursaring a Peat Block and use it from the satchel during a full moon. The moon phase matters. If it's not a full moon, the item won't work. You can rest at camp to advance time until a full moon appears. Peat Blocks come from digging spots that Ursaluna (mount) sniffs out, which is a fun irony.
Yes. Unlike every mainline game before it, Arceus doesn't auto-trigger evolution on level-up. When a Pokemon is ready to evolve, an icon appears in the satchel. You choose whether and when to evolve it. This means you can keep a Pokemon unevolved to learn moves earlier or for Pokedex task completion.
White-Striped Basculin (Hisui-exclusive form) needs to take at least 294 recoil damage total without fainting. Use Wave Crash, Double-Edge, or other recoil moves in fights and accumulate damage over multiple battles. The counter tracks total recoil received across your entire playthrough. Once you hit the threshold, the evolution prompt appears.
Quite a few. Hisuian Qwilfish evolves into Overqwil by using Barb Barrage in Strong Style 20 times. Hisuian Sneasel evolves into Sneasler with a Razor Claw during the day. Kleavor comes from using a Black Augurite on Scyther instead of a Metal Coat. Each new Hisuian evolution has its own specific trigger that ties into the Agile/Strong style system or new items.