Cant form a party now?

[tanukihimself]

So I began the final dungeon in the DLC because it seems like I need to get some trade items from in there to upgrade my equipment to the ascended stuff, and now all my party members are stuck doing the dungeon and I cant form a party when I leave the dungeon to do more sidequests. What is the natural progression of upgrading equipment to ascended stuff? Do I have to go thru the dungeon to collect new trade-able items to upgrade? I dont understand how I am supposed to get the items to beat the final dungeon, if I have to beat the enemies in there to get loot to upgrade my equipment.

[Cowblitz]

The "normal" way would be to buy the standard ascended gear from the Archipelago, that plus being around the same level as the enemies is enough, getting a full set of Rhombus ascended stuff is just extra. Some of the Rhombus Ascended items can also be farmed just from the Archipelago + previous areas, which are:
Ceberus Fang
Medusa Veil
Pegasus Greaves
Chiron Vest
Sunshine Bracer
Skirmisher+
Unbreaking Fist+
Enough to make you a full set, with some weapon options.

Some of the other items also only requires very few of the dungeon materials, which should be acquireable pretty quickly after entering the dungeon since most if not all of it can be ♥♥♥♥♥♥ from the initial outdoor areas.

As far as I know, you can just leave the dungeon and free roam whenever and not a single quest requires party members, although some would be easier for sure. I don't know how it affects the race timer though, if you're concerned with that. I always did every side quest before continuing, so I had little to no reason ever leaving before completion.