Just to be sure... Trooper A has 6th sense and outside of Zero Visibility Zone. Trooper B is in the Zero Visibility Zone. Trooper B moves to engage trooper A. Trooper B is inside ZVZ during the move. Can trooper A declare a BS attack ARO against trooper B?
No. Please see the second FAQ on the Sixth Sense page: http://infinitythewiki.com/en/Sixth_Sense#FAQ Q: A reactive trooper with Sixth Sense is inside Zero Visibility Zone. The active trooper moves into base contact with their first Short Skill and then declares a CC Attack. Can the reactive trooper declare a BS Attack? A: No. The active trooper is only visible when they are in base contact. As BS Attacks cannot be declared while in base contact, the trooper with Sixth Sense cannot declare a BS Attack.
I believe sslv2 just allows you to respond to attacks through zvz without the -6 mod not see through them but I could be wrong.
If you're confused, it's because this FAQ ruling is in direct contradiction to the text for Sixth Sense.
... There are some differences of opinion here; I consider this FAQ to be perfectly consistent with the rule’s text and always though Hecaton’s favored interpretation was incorrect.
It's supported by the rules, but it required you to jump through some pretty serious hoops and do some serious rules wrangling. So as far as "supported" goes, grasping at straws does come to mind as an analogy. The FAQ basically told us the straws held.
So, to turn this around slightly... ...if a trooper with SSlvl2 moved within a ZVZ (smoke) as part of his first short skill declaration and an ARO is generated from an MSV2 trooper; can the active trooper with SSlvl2 respond with an attack as his second short skill of the order...?
Sixth Sense does not grant LOF. If the MSV2 trooper attacks, the active trooper may declare a BS Attack on their second short skill. If the active trooper also has Sixth Sense, then 6S states that they get to ignore the -6 MOD if they choose to respond with BS Attack. If the MSV2 trooper does NOT attack with a BS Attack, then the active trooper will not have LOF for a BS Attack of their own, unless they have a weapon that has No LOF or MSV2 of their own.