New evolution only recently discovered. Looks to be dependent on moves used in battle, so I'm guessing I should be able to bring in a level 100 Primeape from HOME as soon as that's a thing we can do, and it can evolve?
Yes, after using Rage Fist 20 times, you can evolve it using Rare Candy. Similar to Gen 8, any level 100 Pokémon can be evolve using it.
Source: https://bulbapedia.bulbagarden.net/wiki/Rare_Candy
Actually, YES you can... If any Pokemon is at level 100 and requires a level up to evolve, you can use a rare candy on it to trigger evolution