I actually really like your suggestions ginganinja, but i would love to hear the input of others before making any change. Focus Sash sounds nice on paper, but in practice no matter how difficult for Heatran it is to set-up SR, he will do it in one way or another, and then we would have an item-less Terrakion, except if we run a spinner.
For example Heatran can set-up SR by forcing out a weakened Metagross (Meta takes 65% min from Lava Plume), or even a fulll healthy one (which means that it will die by EQ, but who cares, it couldn't do much against team 1 anyway). If something in Heatran's team dies by Thundurus-T, then Heatran can then come in, and set-up SR, as Thundurus-T either fails to ohko with Focus Blast, or uses NP. Either way, Thundurus-T will kill Heatran after the NP, and then it is going to get revenge killed by Mamoswine, which ohkoes after 2 LO rounds most of the times. Finally if Heatran comes into Kyurem, it will always manage to set-up SR, as even after SR, Earth Power will never OHKO. So this shows that Heatran will get many opportunitites to set-up SR if they play suicidally with it. Anyway, what i am trying to say, is that if Heatran is so deadweight and so hard pressed to wall anything against team 1, then the opponenet will realize that all it had to do to be succesful is set-up SR, and will try and achieve only this, even if it means Heatran going down, as it wouldn't have done much anyway.
X-Scissor seems as a great idea, as with it, Terrakion can ohko everything on team 1, so i am definitely replacing it. We won't need SD anyway as it seems.
So what do people thing is the best item for a 3 attacks + SR Terrakion? Focus Sash or LO?
My personal opinion is that we should chose Focus Sash only if 2 things happen:
1. We chose a spinner as the 6th member
2. We chose something for the 6th slot, that only Heatran can handle in team 2. This means that team 2 won't be able to play so reckless with Heatran, and will not be able to sacrifice him just to set-up SR, because then they are going to get swept by our 6th poke. Which means less chances for him to set-up SR.
@ithilanor
There is room for a spinner in the 6th slot, and even if we can't fit one in, Heatran will have a hard time setting up SR, IF we pick something in the 6th slot that only Heatran can check/counter in team 2 (for example Volcarona).