To bump this thread, I've currently been doing Tenzen VD solo with trusts on BLU for a while and figured I'd share my setup and strategy, a lot of which was discussed a while back in this thread. Also, credit goes to Spicyryan who made a video of his solo with trusts, a lot of which my set up is based off of.
Trusts: Qultada, Zeid II, Kupipi, Sylvie (unity), and King of Hearts
-Sylvie is very important for this and greatly increases dps. I suppose you could do it without Sylvie, but it would set you back a lot.
Spellset: Silent Storm, Dream Flower, and Occultation are must haves. Diamondhide is recommended as well. Other than that, stack as much TA/STP/Acc as you can, free to your own personal preferences.
Tizona is essentially a requirement for this as well. While I've never tried this without Tizona, I'd imagine you would run out of mp or be very, very close to doing so. A high magic acc set is also necessary to sleep and silence the tarus (Note. Kukki has high sleep resistance, however can be silenced for a long time. Cherukiki and Makki both can be slept each time.)
Strategy:
Summon trusts. Erratic Flutter, Occultation, Mighty Guard (w/diffusion if up), Diamondhide, and Nature's Meditation. Silent Storm and Dream Flower the Tarutarus. Begin fighting Tenzen. Tenzen will switch to bow form before he gets through all of your shadows (need 550+ blu skill set for a good occultation set). So, don't worry about putting occultation back up until he starts to put away his bow. Make sure to maintain shadows for the remainder of the fight.
*I personally start the fight with Sequence/Colada and switch to Tizona/Sequence once Tenzen uses his first Two Hour ability, Yaegasumi. Then, I build to 3000 tp on tizona and open with Expacion once 45 seconds have passed and Tenzen's 2hr has worn off.*
The tarutarus will likely wake up during the end of Tenzen's Yaegasumi 2 hour ability (uses it anywhere from 73-50% hp). When this occurs, resleep them with Dream Flower. This is very critical because if Cherukiki manages to wake and cast slowga, silencega or diaga, it will completely wipe your shadows and likely kill you. So, you have to reapply sleep right after it wears.
Keep self-skillchaining and keep shadows up. At anywhere from 20% to 49% hp, Tenzen will use his second 2 hour in which he will not take any damage, and will begin using Weaponskills non-stop. At this point, run away (Tenzen is immobile during this 2hr). Also, Tenzen will eat a Rice Ball at anywhere from 20%-55% hp. The longer he waits to eat it, the better, since he gets a significant defense bonus from it.
High dps is the key to this fight. If your damage is lacking, you won't be able to kill Tenzen in time, and he will be able to use Meikyo Shisui as well as some bow weaponskill, wiping your shadows. This fight also takes practice to really become efficient in soloing consistently at a good pace.
My current solo time varies from 5-6 minutes, depending on when Tenzen eats his rice ball and when he uses his 2 hour abilities. This solo isn't bulletproof either, if you're in the middle of your CDC macro and Cherukiki wakes up to cast Slowga and wipe your shadows, and Tenzen SC's you, you're likely dead. But, this rarely happens. I hope some BLUs can find this info useful so that they can solo it for pluton/beitetsu/boulder boxes, as it is an efficient way of making gil atm or saving boxes to AG RMEs.