I’m still not sure I am clear, but from what you describe, this is how I would tackle it.
I would not expect to do one huge shuffle over one or two days and then declare myself done. Rather, I would get into some kind of shape quickly and then adopt a system.
Step 1: Addons
Install three important Addons
Altoholic https://www.curseforge.com/wow/addons/altoholic Altoholic gives you tooltips that show which alt has what items across all your characters.
I can’t say enough good things about Altoholic, or how necessary it is. Being able to see what alt has what, and how much, at all times is a game-changer.
AllTheThings https://www.curseforge.com/wow/addons/all-the-things is less central, but adds to your tooltips information about what each item is for, and what expansion it is from.
Auctionator https://www.curseforge.com/wow/addons/auctionator will show you current price of tradable items if you keep it up to date at the AH now and then, and is especially good combined with the extra tooltip info from the other two.
The addon Postal https://www.curseforge.com/wow/addons/postal may come in handy for all the mailing you are about to do, but it doesn’t have an update for Midnight yet. There is a user-written patch available in the Comments section of the page, but you might not wantto get intoi editing code.
Now log in to all your characters, and get the prices from the Auction House on their realm(s). This will give Altoholic a chance to read and store what they have in their bags and bank.
Step 2: Professions guidance
Bookmark and get familiar with the site
https://www.wow-professions.com/profession-leveling-guides
It gives the most efficient path to level every profession in every expansion.
Step 3: Bank Alts
Create some number of fresh Bank Alts. How many? I don’t know.
Assuming your guild is all of your characters, I don’t expect you will need many, maybe 2 or 3. You will know quickly. For reference, I have 7. (It’s complicated! I don’t need 7 any more, but historically I have played on different realms, and I have no reason to get rid of them.)
Start with 2. Create Level 1s and run them to Orgrimmar, or make an Allied Race or Pandaren Death Knight that starts at level 10 in Org - whatever you are comfortable with.
Buy them biggest bags and max out their bank slots.
Now send everything that is not Soulbound to those alts.
If you have alts on other realms, you can transfer them through the Warbank instead of mailing them. You can even use the Warbak for the same realm.
But do not leave anything in the Warbank. If you leave stuff in the Warbank, it will just become a source of clutter.
Altoholic will keep track of which character has what.
As you are looking at mats and other items, the Auctionator tooltip will show you their price. Do you really want to use a slot on some Classic Essence you can buy for 1 gold?
Or maybe you can list a lot of it on the AH, and collect some cash while cleaning out slots. IDK. Whatever.
If you don’t need it, don’t keep it.
Step 4: The Clean-out
This is the hardest step.
Now that you have cleaned out everything you can from the banks of your main characters, vendor or delete everything you don’t need.
Personally, I keep Legendaries and Legendary mats, though I really shouldn’t. But be ruthless. That old Tier Set? You have the appearance, so you don’t need the items.
I’ve done this at least 3 times over the last 15 years , and I KNOW how hard it is.
Step 5: Choose the Professions
Decide what characters get what professions.
Then go to the Trainers for each expansion, and Train. The site WoW-Professions tells you where to train for each.
Don’t skip this step. It is essential to making a definite structure.
Altoholic will now identify recipes with alts A Tooltip for a recipe will say “Could be learned by Qualix” or something.
Step 6: Redistribute Mats and Recipes
OK. Now go back to your Bank Alts and sort out what Mats and Recipes they need to send to what alts.
This is made much easier by the Altoholic and AllTheThings addon tooltips.
Step 7: Start Skilling up Professions
WoW-Professions makes it easy to skill up profs … usually to about 1/3 or 1/2 of the way. Like, you can probably do that in 15 minutes with an alt shuffling between the trainer and the AH,
At some point, it will get stickier. More expensive mats, or something you have to collect for yourself.
Just skill every alt up in every expansion to that sticking point.
Now check what recipe items you can learn. The alt should already have them.
End of Method
OK, that is how I would approach it.
I would not put anything in the Warbank at all, except as a way to transfer items between characters.
You should now have a clean Warbank.
You may be able to delete your Bank Alts, or you may want to keep them. Up to you, Always handy top have some extra storage for things youwill rarely need, and it keeps clutter out of your Warbank.
Any questions or comments, please post again!