Wily: Random default-profile twitter he posted once to and a default Instagram with photos taken by Cindy on his phone.

Polly: Is on everything, big following, zero media management on any of it.

Phillip: Instagram and twitter that's nothing but cars.

Mahra: Linkedin. (Did not like the horny attention when she tried to have an instagram.)

Prv qrt people and only speaking through reaction images

Jasmine: Instagram to post pics of her camping trips and she would definitely fight in tw*tter about Telenovela theories/ships

Andres: None at first, after starting working at the Naranja academy and getting his ralts he just post pics on instagram of his ralts doing cute things and using tiktok for those 5 minute pastry recipies

Balei is posting cute family photos with the occasional selfie and dance tutorial on Insta

And Fausto has accounts for everyone of his Pokémon where he pretends to be them, except for his Alakazam...he runs his own account, getting into a bit of mischief, all of this the blue bird app

For a comprehensive answer: (https://retrospring.net/@Izetarion/a/108880302840260241 )

Mariah uses poke-world twitter to keep up with global news, but she hardly ever posts anything there; she has a pokegram too but only bc Nia made her make an account lol Mariah just uses it to follow her friends and leave nice comments on their posts when she has a moment…sometimes she’ll post a pic of her Pokémon or a book she’s reading or smthn. I like to think she’d have like a million followers even tho she never posts anything fhdkjd

Dawn: has a largely personal blog with photos of her home and (when it eventually became knowledge that she and Dusk were dating) pics of him and snippets from dates. Various "this makes me happy" kinda deal.

Dusk: has a bird-app-esque kind of account he made to follow figures for entertainment, be they Iono's slip-ups, Raihan's league info-dumping, or Steely's misadventures on stream. Dusk does, however, have several viral videos of Jen swearing.

Star: More akin to a travel blog with various photos of scenery, pokemon, and her friends. She has quite the eye for composition and could make for a stellar photographer.

In the tabletop community I'm in, there's a local chatroom service the trainers (and some Pokemon!) use as a means to get info or just have a chat!
But in terms of real world social media sites, Ming-Ming would be an avid fan of Insta for showing off her Pokemon or cooking recipes, Tiktok just to watch some funny videos. She's a bit of a trendy girl in that sense!

Tyler would be the kind of guy who would post pictures of the scenery he's in like some kind of blogger, and he would also post pictures of his battles, even his losses

Basically he's a mini Raihan

I think Odd would predominantly use Insta, mainly to post images/promotions regarding his shop, and to document whatever misadventures his Pokemon or himself got into that day.

He used to go on Twitter more often (and occasionally will sneak on to check out what his friends post), but with the discourse rabbit holes he had a tendency fall in when he was feeling down, Mauve tries to keep him away from the bird app

And occasionally he'll boot up Tumblr; when asked why he uses it, he'll respond "A walk through a wasteland can be refreshing, sometimes."

Eve: Would definitely post pics of her Pokémon, scenery from regions she's currently visiting, and food.
Ryoko: Shouldn't be allowed to have a phone to begin with but would probably spend most her time talking shit on the blue bird app, probably get suspended
Milja: she's still sending Murkrows to deliver mail she's never touched the Internet
Harriet: You just know she's on all the platforms to brag

Stahl has other people run his social media for him. He is blissfully unaware of the chronically online.

Arryn has an instagram where she posts pics/vids of her pokemon and workout routines. She has a lot of followers, half join for pics of legendary pokemon she chases for fun and the other half stay for thirst traps and ab pics.

Avian has a work twitter as a gym leader. despite this he was unverified back when verification meant a damn