incredibly informal depending on who they address. if they like someone and they have a title they will treat them really respectfully but otherwise friends are talked to informally with the occasional swear but they arent a sailor

For Norrie it depends on who she's speaking with, she speaks more formally when she's doing something in public or around the "high class" kind of people.

I've mentioned this before but the only "high class" person that allows her to truly be herself is Ohtli!! Norrie can take a breather and is allowed to speak more "like a commoner", if she's around people she's comfy with she rather call them by nicknames too! She calls Ohtli "Goldie" cuz of her eyes for an example hehe, also I like to think she has a little bit of an accent since eng is her 2nd language.

Nettle speaks with relative politeness, or well. Professionalism. Doesn't swear much.
Astra cant be formal if her life depends on it <3. Swears every other sentence.
Orchid is professional. Swearing is even rarer than nettle doing it.
Weiss is professional but she swears every sentence so i'm not sure how that comes across.

depends on who she's speaking to, however her language will often be more informal. she does try not to swear in front of people older than her, people she respects, or during her gym challenge, but a swear or two might just pop out if she's not paying too much attention.
she's the most polite with them grandmas and grandpas. she respects the elderly.

Kingston: Mostly formal, generally quite well spoken because it comes with being a lawyer ;u; unless he's with friends or ppl v close to him where he can be less restrained (eg; bantering w didier or letting his sarcasm slip out a bit more.)

Ruth: Polite and soft spoken, has trouble expressing herself ;u; She rarely uses slang but she has a tendency to use certain idioms that aren't commonly used just because she hasn't interacted much with people her own age and picks up her vocabulary/speech patterns from books she's read.

Dory obviously speaks in a Spikemuth Accent, is fairly formal, and occasionally curses.

Visi has a little bit of a Spanish accent but it’s easy to miss aside from a few words. He also doesn’t curse much.

Ilex is really formal.

Due to her upbringing Mary is pretty formal in her speech most of the time...but when she's mad she dips into the more "colorful" language she learned living at her aunt's inn.
Jin's speech is pretty casual but there are times she can't help herself and she starts speaking in an almost poetic way, like the story books she loved as a kid.

Actually Grim's speech is very formal around strangers and challengers and some other people, and it gets a bit informal with friends and acquaintances but not too much. He does swear a lot tho, but like, politely. And he has a slight British accent since he's half Galarian, sometimes is not noticeable but is there !

Lionel: Polite but not posh.

Estella: Switches from posh to crude entirely depending on her mood

Heather: A bit high class, but when she's made she sounds very rural

Lex: Tends to be over the top and hammy, but I wouldn't call it posh or formal.

Shayla: Rural and chill.