I've seen someone run around with a companion in Power Armor, so at least they, or some of them, can use it.
Settlers can equip the armor, and so can companions. Not tried it yet, but have you tried assigning a settler to armor? Failing that, just leaving the armor out, with a core inside it, eventually one of the settlers will take it out for a spin.
I discovered by accident that settlers will use power armour to defend their settlement and then abandon it to go back to their assigned duties. This happened when I left my PA at Sanctuary to go building at another settlement and when I came back to Sanctuary a raid was in progress and my PA was being used by a settler who just abandoned it in the middle of town when the battle was over. The head was missing and it was ages before I found it again in a different settler's inventory.
So now I leave PA frames with whatever spare armour pieces I have in various settlements but without fusion cores. So if a raid happens then the nearest settler will jump into the PA and use it in defense of the settlement. I don't want them to burn up my fusion cores but they might as well benefit from my spare armour. You don't always get a warning that a settlement is under attack so it's best to give your settlers every chance possible to defend themselves.
I leave the best spare armour in the smallest settlement as they will need it more. I also remember to take my own armour with me everywhere even if I don't intend to use it so settlers won't lose bits of it again.
Your companion can use it. Point at your companion and press 'command' and then point at the power armor and say "enter power armor." It can be a little finicky though. Sometimes you have to move around the power armor a bit before the right icon pops up.
I've seen settlers jump in the power armor when the settlement has been under attack as well. I'm not sure if you can actually permanently equip the settlers to a given suit of power armor or anything like that though.
What you did not discover yet is that raiders attacking your settlement can use it as well And you will loose your power armor frame by killing them.
Settlers won't use it if it does not have power core. But raiders will not either
Thanks for the tips, arras. I'll just use my spare armour as nice statues for the raiders to look at when they spawn in the middle of my towns.
I wish there was some way to sell off extra frames, you only really need 1, then you can deck it out with whatever combination of parts you found you want, for any situation, I have a ton of extra frames standing around but don't know what to do with them, making extra suits doesn't really make any sense, I can only wear one at a time after all
I just got my third suit, from ejecting Tessa. I was shocked at how easy it was to target the core when she was busy fist fighting with Cait. I have never seen a settler fool around with them though, and I have one parked right outside the barn in Sunshine Tidings Co-op, overlooking my crops.
I won't let my settlers use it. I keep them all lined up in a room I built, like a post-apocalyptic Tony Stark.
Once you know the what signs to look out for you can find it very easily, there is power armor literally everywhere.
Crashed vertibirds and military bases with locked up armories are prime places to search, I had well over 10 half-built frames standing around my settlement by the time I was level 15.
All I wanted was to find enougb parts so I could make 2 or 3 complete suits, but all the ones I found are missing the left leg....some wasteland thief went around after the war stealing all the left legs off power armor for some reason, I don't know why that is the one piece that is always missing.
I've converted the Red Rocket's workshop into my bedroom. Outside the roller door I've built my sealed armoury with all my crafting stuff, weapons storage, and places for one set of each power armour in the game. It's pretty cool hitting the button and watching one wall slide away to reveal all the crafting gear and then walking around the corner to see a row of power armour. I'm just hoping settlers don't know how to open the shutter...
Mine are all lined up on top of my floating fortrees above the drive in lol you can only fast travel in. When mods come around to replace with high end materials and not look so ratty, it'll be a pretty awesome looking superfort
As for settlers getting into them, I wouldn't know, since it is one aspect of the game I haven't touched, and probably won't. But, raiders and followers can enter a power armor if it has an equipped core. Maybe same goes for settlers?