A few more results of my experimentation (should I make a separate topic for this where it's compiled on one place?):
Yesterday, I was attempting to give a newly-hatched Pokémon the Pokérus by running from wild encounters, but I was unsuccessful at it for hours. I discovered a second condition I overlooked: To spread the Pokérus by running from wild encounters, you must bring out a Pokémon with the Pokérus in its infectious stage. I don't know if it has to be in the initial slot or if you can switch in to a Pokémon with an infectious Pokérus, however.
Cursola's Perish Body takes effect even if the contact move knocks it out. This may actually be an easier application of Perish Body than to let it take a hit and switch in to something that can trap it, since when Cursola is knocked out, you have to immediately replace it with something--might as well do it with a Pokémon with Arena Trap or Shadow Tag. (Or Magnet Pull once Meltan is made available.) That is, Cursola's role on a team is to sacrifice itself to ensure taking out an opponent's Pokémon that might otherwise give a lot of trouble. Cursola's low Defense suggests switching it in when you expect your opponent will use a contact move. Excadrill, Gyarados, Arctovish, Corviknight, Mimikyu, Zacian, and Zamazenta all rely on contact moves to some degree, making them potential victims of Perish Body. Which brings me to my next point...
Max Moves and G-Max Moves do not make contact, even if the moves they're based on do. It's a situational thing, but there are a lot of moves, Abilities, and other factors that differ depending on if you use a contact move or not, and this can be one potential way to get out of a sticky situation, such as if the opposing Pokémon is wearing a Rocky Helmet, has Iron Barbs and/or has used King's Shield. This also means that Pokémon with Tough Claws do not get the 30% damage increase from Max Moves; depending on the moves, a Pokémon with Tough Claws might less damage when Dynamaxed. (There are currently no Gigantamax Pokémon with Tough Claws, at least under normal circumstances.)