Need help farming all Hr6 diablos

I assume you need horns mostly, so hammer is a really bad idea since the head takes extremely low impact damage, and you'll want to break the horns to get them in the rewards.

LS is okay, but it can get a bit dangerous while you're attacking the head, and blos decides to roar-charge while raged. It sure can be handeled, but I find other weapons better.

GS - a solid choice if you know how to charge the horns and tail stub.
If you go for GS, go for Hidden Blaze + Ceana S. The way you gemmed it is optimized already.

HBG is also a solid choice. I'd recommend a mix of Narga S and Conga U, gemmed for Evade Distance Increase, Pellet S Up and depending on what you prefer, either Constitution or Bomber.
The tectic is simple - grab a gun with good Pellet R clips and not too slow reloading speed, then pellet his horns till they break, then continue pelleting the tail.

LBG - The HR6 Chameleos with full Shinobi Heaven is a fair choce. Gem for Element Attack Up, Evade +2 and utoreload, then break the horns using Ice and Thunder S. Once broken try shooting the rest of these shots through the full lenth of his tail. If you run out of ammo, continue using Normal 2. Bring enou huskberry and needleberry to make sure you have enough normal 2 to kill it. You can also bring the combines for Pellet 3 if you like, but the recoil will be pretty tough.

My personal choice would be the GS, but to each his own.

Thoracic is no break reward, so just killing / capturing does the job in this regard.
Shock Traps work, but if Blos digs or resurfaces under them, he will break them. I'm also not recommending them. I find it quite important to get used to not use traps, even more so for G Rank, but how you play is your choice.

Ah ok, for capturing I use them too.
It doesn't seem to make too much of a difference for the rewards on blos whether you capture or kill, but blos goes into rage mode after every hit from a certain point onward. It makes him a bit harder to handle, but it's also a signal for you that he can be captured soon.
Hit him a few more times, then attempt to capture if you want to avoid that 1-hit-rage. If you don't mind it, then just kill away.

You (nearly) never see blos limp becaus he doesn't when he is in rage, and since he goes into 1-hit-rage before he starts limping he'll spent nearly the rest of the battle in rage. However, not too long after his 1-hit-rage-crap starts, he is ready to capture. Was one of the few things that I figured out really really late in the game. Never bothered.

Then use Hidden Sabre with Ceanataur S^^
I personally just get a level 2, regularly even a level 3 charge in most of the time when Blos digs, and that does quite some damage to Blos.
If you're better of with LS, then by all means go for LS.