I want to move from red rocket to the castle, but I don't know how, I already have settlers at the castle, but I want to move all my stuff like my 6 sets of power armor and other things. How do I move?
There's no concept of a "home base" in the game, so there's no support for switching from one base to another.
You own both settlements, and have stuff at both settlements. In the eyes of the game, they're the same.
If you have some things you would like to move from one settlement to another, such as power armor suits or weapons, you'll have to manually move each piece.
Moving the Stuff
You could carry the items yourself, or you could get NPCs to carry it.
If you trade with a settler or companion in one settlement, you can fill them up with gear, then move them to the other settlement. Keep in mind that travel between settlements is not instant, so you might need to wait a bit for them to show up on the other end.
With rank 4 of the Strong Back perk, you can fast travel while overencumbered. If you have this, you can move everything but the power armor all at once.
Obviously, you can only wear one power armor suit at a time, and you can't carry them in your inventory. This means that someone will need to wear the suit to move it from location to location. Again, this doesn't have to be you. A companion following you can wear a suit, and won't drain its core.
I've had success putting a companion in power armor and sending them to another settlement, but some people have reported them showing up without the armor, so be cautious if you try this.
See this question for more information on moving power armor.
You're probably aware, but just in case, note that supply lines can allow you to access crafting materials from connected settlements. Therefore, if you have supply lines, there's no need to move junk or other crafting materials like mods or crops.
- Junk and Food items can be stored in any Workshop, and then shared with other settlements by setting up Supply Lines (You will need the Local Leader Perk in order to set up Supply Lines).
- Other types of items (Weapons, Clothing, Aid etc) will need to be manually loaded and fast-traveled to the new location. The Strong Back perk can help with this, and at Rank 4 you can even fast travel while over-encumbered, meaning you'll only need to make one trip.
- Another alternative is to load a Settler up with all the items, and send them to the new location. However, they will need to walk there and will take some time to show up.
Moving Power Armour
- Fast-Traveling whilst wearing Power Armour does not drain the Fusion Core, so you can simply hop in, fast travel and hop out to move your Armour to and from. A little tedious but ultimately the only easy way to move them.
- A human companion capable of wearing Power Armour can also help with this. They do not drain the power cores at all while wearing them.