In other parts of the country that's not common and people see "guys" as gendered, and people feel like you're forgetting they're there.
The word "dude" as a form of address is gender neutral and business appropriate some places and not others.
It's a hard problem: Y'all works some places but sounds goofy and affected in others. Same with "folks."
If I know that some phrase is really uncommon or has different shades of meaning in a different part of the country or a different part of the world, I also know that if I use that phrase in that other place, it will get interpreted differently from what it means to me. It can be frustrating if I haven't yet picked up on the differences, but it's just the nature of communication.
I have also tried to hang on to "y'all" and "folks" since moving to the west coast. "Folks" is a harder sell though, when I use it feels more like an affectation. But that's my perception of others' perceptions. Maybe I'm pulling off "folks" without realizing it. But "y'all" has more staying power, because it's a legitimately useful term that's otherwise missing from the English language.
One less fraught, but equally confusing terms are "a couple" vs. "a few" vs. "a handful" (some believe "couple" = 2 whereas others treat it and the others as explicitly more fuzzy). Often it's best to just assume as little context as possible and be a little more explicit and verbose.
As a result, I've gotten into the habit of saying "y'all" and "folks" even though I'd otherwise never have used these words.
Hey everybody!
Listen up people
All,
What each of you needs to do...
I have a task for all of you
Let’s all have a great time
Alright gentlemen and lady,
Everyone on the team should read this
This applies to everyone on the team
Any person on the team can do xyz
If you see something, say something
Thou hast best checkest thyself, ‘ere thee wreckest thyself!
So what's the acceptable format? "guys, gals, and... others?"
Please make sure to put a cover sheet on your TPS reports.
Team,
Please make sure to put a cover sheet on your TPS reports.
Everyone,
Please make sure to put a cover sheet on your TPS reports.
Good Afternoon/Morning,
Please make sure to put a cover sheet on your TPS reports.
Staff,
Please make sure to put a cover sheet on your TPS reports.
I just quickly browsed through my emails I've received this year (coworkers, customers, vendors) and that covers all the ones I've received. All of those are perfectly acceptable.
I wouldn't be personally use "guys," "gals," or "guys and gals" in a non-friend situation.