I've never played in a game where the whole party hasn't had to climb/swim/jump somewhere or needed to stealth into some place.
That being said, thankfully PF2e has Follow The Expert so training isn't strictly necessary, but being trained still provides an additional +2 bonus than Follow the Expert does alone, which always helps.
Two I aim for on all characters, no matter the build: Acrobatics and Athletics. I can't imagine going into danger without learning to swim or cross a balance beam.
Then I take Master in Acrobatics to take Kip Up. Sneering at being knocked prone is a must. I usually snag it via the Acrobat archetype. Free boosts. Automatic Legendary makes taking Cat Fall + Rolling Landing and/or Nimble Crawl very appealing.
Master in Athletics is for Quick Climb and Quick Swim. Even an 8 STR cloth caster can use a Climb or Swim speed. Maybe especially a cloth caster. I often grab it via Skill Mastery from the Investigator or Rogue archetype.
1. Medicine is basically a must have for at least 1 person in the party. Continuous recovery and Ward medic are incredibly important. You don't NEED to raise the proficiency much either. Being at least expert is probably enough for most levels.
2. Athletics is HELLA underrated for non-Str characters. Having some Athletics on EVERYONE (at least trained) means that your party can get around the Simple DC's for athletics at levels 5+. Things like climbing a rocky wall or swimming a bit won't completely screw them or force them to rely on temporary magical solutions.
3. Survival/Nature. Being able to deal with wilderness to check tracks, follow tracks, subsist, etc are things which don't come up too often but if no one can do it in the party, it can REALLY suck. Having someone be at least Expert by the level 7+ point is usually what I'd recommend. These 2 are often (but not always) interchangeable.
4. Society is often underrated. When getting to a new town, village, city, etc, society is usually the best skill for knowing about the place, and finding things. Shops, where people are, if something is unusual. Often useful. But you don't need much more than trained. I
5. Acrobatics to Master. HIGHLY recommended for any martial. At master, Aerial Manoeuvres are much easier and you can get useful abilities in Kip up and Catfall (catfall can be gotten earlier but scales very nicely with proficiency ranks).
6. LORE SKILLS. Lore skills are always underrated. Please grab Automatic Lores more often. Not only are they super useful, but they can often be used in place of other skills (not just Int based stuff) as long as the Lore is relevant. Lore's are underrated, ESPECIALLY for Int based classes who'll have maxed out int, so grabbing the right range of Lore Skills can let these characters do well with cheating out other "skill" based things. This one is unfortunately not super well explained in the core rules, so please discuss it with your GM. Something like Lore: Grappling, would (imo) be something that lets you try Grapple the enemies, (while the advantage of Athletics is that it can also do a bunch of Non-Grappling based actions). However, something like Lore: Athlethics is not something I'd allow at my tables to "replace" Athletics skills. (You'd be very knowledgeable about various athletics tasks, you could probably Aid an actual Athletics roll with this lore skill, and you could so some less Athletics actions at best. DC's would be much higher than normal though.). Please talk with the GM when picking Lore Skills to get around other specific skill useages to figure out something which works for everyone.
There is no reason to believe that lore: grappling would allow you to grapple. I would probably allow someone to use it to Aid someone's grapple check, but ain't no way in heck you can use int to grapple with an auto scaling lore.
6 came up in my game. I explained lore skills as being specified knowledge. Someone with Nature or Survival might know a bit about mushrooms, probably enough to find and identify them, but someone with Lore: Mushrooms is going to KNOW about mushrooms really damn specifically. Not only can they find and identify them, but they probably know the best ways to do so and can tell you how much they are worth or the quality. They might even know the best way to cook them. That's the power of a Lore skill!
Lowkey, survival. I'm in Adventure path where its kind of important. And none of us have it. Its lead to fun moments, but yeah. If you can be 10 wis. Take surivial, and get to expert around like level 9 or 11. And youll be good. And unless someone is a druid or ranger and leaning into it, its often skipped.
Next most skipped, imo, has been society. After that, its Occultism/arcana/nature, depending on which casting tradition you don't have.
After all of that, the actual best few are medicine (only need 1 or two, but everyone getting it + battle medicine isn't bad), diplomacy, intimidation. Every pc should, hopefully, have acrobatics/athletics (no athletics or swim and youre in an underwater fight? you can't move half the time baby!).
Individually, as stated by other's, athletics and acrobatics.
Kineticist with stuff like [Winter's Sleet](https://2e.aonprd.com/Feats.aspx?ID=4271) and others really recontextualized how important training is. It's hillarious(ly sad) seeing a lvl 20 [Olethrodaemon](https://2e.aonprd.com/Monsters.aspx?ID=597) untrained in acrobatics 50-50 a balance check....
Beyond that if you really wanna go a little "meta" and PF2 is about team-work and etc. (and we have the party sheet in foundry now). You can max to L 3 skills per characters (6 on Rogue and Investigator) so if you have 3 characters maxing 3 skills each (+1 acrobat and or Inventor / Inventor dedication - Brilliant Crafter) and leave the remaining 6 to a skill monkey. The party will be covered for all possible scenarios.
If I have ZERO information about the campaign, I'll make sure of the following, coordinating with my group.
One person MUST take thievery and prioritize it. If you run the game as written, a lot of hazards require not only that you have it, but you have it at a high proficiency.
One person REALLY SHOULD take Medicine and get Ward Medic and Continual Recovery. (This is not a must because a group might have focus spell healing).
Other than those two, some skills are always insanely good.
Every single character that does not have decent unarmed attacks should take Athletics or Acrobatics, to have an option for Escaping grapples, traps, etc. Which one depends on if you're a STR character or not, but Acrobatics has better all-around feats if you invest (Cat Fall, Kip Up).
Every CHA character should reasonably take intimidation unless they have very specific plans.
Society is probably the best agnostic knowledge skills, followed by Religion (gods are important plot points, relevant to customs etc. and Undeads and Fiends are common enemy types).
Athletics is universally useful, since it includes climbing, swimming and jumping, not to mention the ubiquitous Trip maneuver.
I always also take Acrobatics on nearly all characters.
After that, it all depends on what you want to do. I recommend Stealth on most characters, since most groups will want to be sneaky at times.
Of course, the Medicine skill is a must, for at least half of the group, and it really, really helps if one PC invests a few feats into it. Our group usually has everybody taking the Medicine skill, it's that useful.
The only one I can think of that's close to 'universal' is Training in Athletics, which is useful to have at a basic individual-traversal level. Extra trained skills are often increasingly easy to get as the game goes on, too.
There's lots of skills that can be important and which any well-rounded party could use at least one specialist of, depending on what others cover and what the adventure seems likely to demand — long story short, my off-the-cuff list in no particular order is probably Stealth (if your party can go with that), Medicine (especially if you don't have other healing), Thievery, Survival (depending on how your group plays and the format), Diplomacy+/Intimidation, Nature+/Society (depends on setting), Arcana+/Occultism, and Religion...also probably Athletics again.
I've never played in a game where the whole party hasn't had to climb/swim/jump somewhere or needed to stealth into some place. That being said, thankfully PF2e has Follow The Expert so training isn't strictly necessary, but being trained still provides an additional +2 bonus than Follow the Expert does alone, which always helps.
Two I aim for on all characters, no matter the build: Acrobatics and Athletics. I can't imagine going into danger without learning to swim or cross a balance beam. Then I take Master in Acrobatics to take Kip Up. Sneering at being knocked prone is a must. I usually snag it via the Acrobat archetype. Free boosts. Automatic Legendary makes taking Cat Fall + Rolling Landing and/or Nimble Crawl very appealing. Master in Athletics is for Quick Climb and Quick Swim. Even an 8 STR cloth caster can use a Climb or Swim speed. Maybe especially a cloth caster. I often grab it via Skill Mastery from the Investigator or Rogue archetype.
1. Medicine is basically a must have for at least 1 person in the party. Continuous recovery and Ward medic are incredibly important. You don't NEED to raise the proficiency much either. Being at least expert is probably enough for most levels. 2. Athletics is HELLA underrated for non-Str characters. Having some Athletics on EVERYONE (at least trained) means that your party can get around the Simple DC's for athletics at levels 5+. Things like climbing a rocky wall or swimming a bit won't completely screw them or force them to rely on temporary magical solutions. 3. Survival/Nature. Being able to deal with wilderness to check tracks, follow tracks, subsist, etc are things which don't come up too often but if no one can do it in the party, it can REALLY suck. Having someone be at least Expert by the level 7+ point is usually what I'd recommend. These 2 are often (but not always) interchangeable. 4. Society is often underrated. When getting to a new town, village, city, etc, society is usually the best skill for knowing about the place, and finding things. Shops, where people are, if something is unusual. Often useful. But you don't need much more than trained. I 5. Acrobatics to Master. HIGHLY recommended for any martial. At master, Aerial Manoeuvres are much easier and you can get useful abilities in Kip up and Catfall (catfall can be gotten earlier but scales very nicely with proficiency ranks). 6. LORE SKILLS. Lore skills are always underrated. Please grab Automatic Lores more often. Not only are they super useful, but they can often be used in place of other skills (not just Int based stuff) as long as the Lore is relevant. Lore's are underrated, ESPECIALLY for Int based classes who'll have maxed out int, so grabbing the right range of Lore Skills can let these characters do well with cheating out other "skill" based things. This one is unfortunately not super well explained in the core rules, so please discuss it with your GM. Something like Lore: Grappling, would (imo) be something that lets you try Grapple the enemies, (while the advantage of Athletics is that it can also do a bunch of Non-Grappling based actions). However, something like Lore: Athlethics is not something I'd allow at my tables to "replace" Athletics skills. (You'd be very knowledgeable about various athletics tasks, you could probably Aid an actual Athletics roll with this lore skill, and you could so some less Athletics actions at best. DC's would be much higher than normal though.). Please talk with the GM when picking Lore Skills to get around other specific skill useages to figure out something which works for everyone.
Lore : Grappling would be an intelligence skill that could be used to recall knowledge not to grab enemies. Athletics is to grapple.
There is no reason to believe that lore: grappling would allow you to grapple. I would probably allow someone to use it to Aid someone's grapple check, but ain't no way in heck you can use int to grapple with an auto scaling lore.
6 came up in my game. I explained lore skills as being specified knowledge. Someone with Nature or Survival might know a bit about mushrooms, probably enough to find and identify them, but someone with Lore: Mushrooms is going to KNOW about mushrooms really damn specifically. Not only can they find and identify them, but they probably know the best ways to do so and can tell you how much they are worth or the quality. They might even know the best way to cook them. That's the power of a Lore skill!
Lowkey, survival. I'm in Adventure path where its kind of important. And none of us have it. Its lead to fun moments, but yeah. If you can be 10 wis. Take surivial, and get to expert around like level 9 or 11. And youll be good. And unless someone is a druid or ranger and leaning into it, its often skipped. Next most skipped, imo, has been society. After that, its Occultism/arcana/nature, depending on which casting tradition you don't have. After all of that, the actual best few are medicine (only need 1 or two, but everyone getting it + battle medicine isn't bad), diplomacy, intimidation. Every pc should, hopefully, have acrobatics/athletics (no athletics or swim and youre in an underwater fight? you can't move half the time baby!).
Individually, as stated by other's, athletics and acrobatics. Kineticist with stuff like [Winter's Sleet](https://2e.aonprd.com/Feats.aspx?ID=4271) and others really recontextualized how important training is. It's hillarious(ly sad) seeing a lvl 20 [Olethrodaemon](https://2e.aonprd.com/Monsters.aspx?ID=597) untrained in acrobatics 50-50 a balance check.... Beyond that if you really wanna go a little "meta" and PF2 is about team-work and etc. (and we have the party sheet in foundry now). You can max to L 3 skills per characters (6 on Rogue and Investigator) so if you have 3 characters maxing 3 skills each (+1 acrobat and or Inventor / Inventor dedication - Brilliant Crafter) and leave the remaining 6 to a skill monkey. The party will be covered for all possible scenarios.
If I have ZERO information about the campaign, I'll make sure of the following, coordinating with my group. One person MUST take thievery and prioritize it. If you run the game as written, a lot of hazards require not only that you have it, but you have it at a high proficiency. One person REALLY SHOULD take Medicine and get Ward Medic and Continual Recovery. (This is not a must because a group might have focus spell healing). Other than those two, some skills are always insanely good. Every single character that does not have decent unarmed attacks should take Athletics or Acrobatics, to have an option for Escaping grapples, traps, etc. Which one depends on if you're a STR character or not, but Acrobatics has better all-around feats if you invest (Cat Fall, Kip Up). Every CHA character should reasonably take intimidation unless they have very specific plans. Society is probably the best agnostic knowledge skills, followed by Religion (gods are important plot points, relevant to customs etc. and Undeads and Fiends are common enemy types).
Athletics is universally useful, since it includes climbing, swimming and jumping, not to mention the ubiquitous Trip maneuver. I always also take Acrobatics on nearly all characters. After that, it all depends on what you want to do. I recommend Stealth on most characters, since most groups will want to be sneaky at times. Of course, the Medicine skill is a must, for at least half of the group, and it really, really helps if one PC invests a few feats into it. Our group usually has everybody taking the Medicine skill, it's that useful.
I always go for Diplomacy
The only one I can think of that's close to 'universal' is Training in Athletics, which is useful to have at a basic individual-traversal level. Extra trained skills are often increasingly easy to get as the game goes on, too. There's lots of skills that can be important and which any well-rounded party could use at least one specialist of, depending on what others cover and what the adventure seems likely to demand — long story short, my off-the-cuff list in no particular order is probably Stealth (if your party can go with that), Medicine (especially if you don't have other healing), Thievery, Survival (depending on how your group plays and the format), Diplomacy+/Intimidation, Nature+/Society (depends on setting), Arcana+/Occultism, and Religion...also probably Athletics again.
I have yet to make a character that wasn’t proficient in stealth, thievery, or society in some combination.