My thoughts on your missing factions:
I tried Eldrazhor a lot without potions and for me, it would be completely “red”, following your colour table. I finally did it on a Tuesday. The problem for my mental health was the enemy team in the first room, because it uses two Elven Rogues. You can not kill them as long as the other two troops are still alive and they will very likely get enough mana to reduce your attack to 0. Then you have to rely on instant kill or the (slow) damage to all of Deep Magus. So the first fight usually is a very long and annoying one, that you will win in almost every try, but it takes a lot of time and still you are not sure to get a successful run. So you are wasting a lot of time for basically nothing. After some weeks, i got so frustrated, that I banned Eldrazhor to my Tuesday list…
For Hall of Guardians I used the same team, that @kamosloki has also shown. As others have said, the Golem is the key to success here, as it helps a lot with its stun.
For Sea of Sorrow I used Hammerclaw, Sea Witch, 2x Deep King. My hoard level here was 199, so still not too high. It is also very luck based, as the Sea Witch can loop very well - if you get lucky. If you are unlucky, she just hands over the perfect board to the enemy. Also, the main unit is Deep King, but you can´t influence the enemies he is damaging. I had many tries, where I was able to reach the final battle, but didn´t make it, because my Deep Kings decided to kill every enemy except the enemy Deep King. And once he casts for the second time, you are basically done. However, if you get lucky enough to get decent loops with Sea Witch an kill the enemy King early (or deny his mana), it is at least doable.
Werewoods I finished just last week, my hoard finally was 221. I tried a lot with various teams, success came with a very simple approach of just 4x Torben. During various runs I found, that Torben´s skill is by far the strongest weapon you have. Creating a lot of skulls and reds AND giving hunter´s mark to the first two enemies AND giving you an extra turn (as long as you cast it carefully) is very powerful. A good Torben cast will often eliminate two enemies at once. So it is important to have at least one, better two Torbens, when going into the final battle. As your team will transform a lot, this is not so easy, which is why I decided to start with the maximum possible number of Torbens. Of course, there was also some luck involved, but I tried only once with the 4x Torben team, the very first run was successful.
I also tried Fang Moor without potions, but finally did it on a Tuesday. With high stats, it is doable, so it is just a matter of hoard level. My hoard level was 177, when Fang Moor arrived on a Tuesday and I had time on this Tuesday, so I decided to go the easy way. It was a cakewalk with 5 potions of power and didn´t require a lot of strategy, which is why I think, that you can also do it, if your hoard is just big enough. But “big enough” could be something about 250-300 or even higher here…
I did The Labyrinth and Hell Gate during their release weekends, so no idea on a PF run without potions for them.